<?xml version="1.0" encoding="UTF-8"?>
<!-- Documents rendered in XBRL format prepared by Certent CDM XBRL Version: 10.3.0.0.26 (5021) using Fujitsu Interstage XWand -->
<!-- Validation status: Passed -->
<linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/instance http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
    <roleRef roleURI="http://www.harvardbioscience.com/role/AccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_AccumulatedOtherComprehensiveIncomeDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/AcquisitionsDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_AcquisitionsDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/AcquisitionsNarrativesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_AcquisitionsNarrativesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/CapitalStockAssumptionsBlackScholesAndMonteCarloDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_CapitalStockAssumptionsBlackScholesAndMonteCarloDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/CapitalStockDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_CapitalStockDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/CapitalStockNarrativesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_CapitalStockNarrativesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/CapitalStockStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_CapitalStockStockbasedCompensationExpenseDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/CapitalStockStockOptionsAndRestrictedStockActivityDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_CapitalStockStockOptionsAndRestrictedStockActivityDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/CapitalStockTables" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_CapitalStockTables" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/ConcentrationsNarrativesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_ConcentrationsNarrativesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/CONSOLIDATEDSTATEMENTOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_CONSOLIDATEDSTATEMENTOFSTOCKHOLDERSEQUITY" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/DerivativeDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_DerivativeDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/DerivativeNarrativesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_DerivativeNarrativesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/DerivativeOtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_DerivativeOtherComprehensiveIncomeLossDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/EmployeeBenefitPlansDefinedBenefitPlanDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_EmployeeBenefitPlansDefinedBenefitPlanDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/EmployeeBenefitPlansPlanAssetsDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_EmployeeBenefitPlansPlanAssetsDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_FairValueMeasurementsDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/GoodwillAndOtherIntangibleAssetsDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_GoodwillAndOtherIntangibleAssetsDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/IncomeTaxNarrativesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_IncomeTaxNarrativesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/LongTermDebtBorrowingsDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_LongTermDebtBorrowingsDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/LongTermDebtNarrativesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_LongTermDebtNarrativesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/PropertyPlantAndEquipmentDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_PropertyPlantAndEquipmentDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/RecentlyIssuedAccountingPronouncementsDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_RecentlyIssuedAccountingPronouncementsDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/RelatedPartyTransactionsNarrativesDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_RelatedPartyTransactionsNarrativesDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/RevenuesDeferredRevenueDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_RevenuesDeferredRevenueDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/RevenuesDisaggregationDetails" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_RevenuesDisaggregationDetails" />
    <roleRef roleURI="http://www.harvardbioscience.com/role/RevenuesTables" xlink:type="simple" xlink:href="hbio-20190630.xsd#ELRID_RevenuesTables" />
    <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" />
    <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" />
    <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" />
    <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" />
    <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" />
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/CapitalStockTables">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="Locator_us-gaap_ValuationTechniqueDomain_657" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BlackScholesOptionPricingModelMember" xlink:label="Locator_hbio_BlackScholesOptionPricingModelMember_658" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ValuationTechniqueDomain_657" xlink:to="Locator_hbio_BlackScholesOptionPricingModelMember_658" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="Locator_us-gaap_ValuationTechniqueDomain_659" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MonteCarloValuationSimulationMember" xlink:label="Locator_hbio_MonteCarloValuationSimulationMember_660" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ValuationTechniqueDomain_659" xlink:to="Locator_hbio_MonteCarloValuationSimulationMember_660" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_661" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:label="Locator_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_662" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_661" xlink:to="Locator_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_662" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_651" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_652" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_651" xlink:to="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_652" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_653" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="Locator_us-gaap_ValuationTechniqueAxis_654" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_653" xlink:to="Locator_us-gaap_ValuationTechniqueAxis_654" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="Locator_us-gaap_ValuationTechniqueAxis_655" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="Locator_us-gaap_ValuationTechniqueDomain_656" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_ValuationTechniqueAxis_655" xlink:to="Locator_us-gaap_ValuationTechniqueDomain_656" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="Locator_us-gaap_ValuationTechniqueAxis_663" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="Locator_us-gaap_ValuationTechniqueDomain_664" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_ValuationTechniqueAxis_663" xlink:to="Locator_us-gaap_ValuationTechniqueDomain_664" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/GoodwillAndOtherIntangibleAssetsDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_727" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_728" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_727" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_728" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_745" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_746" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_745" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_746" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_737" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PatentsMember" xlink:label="Locator_us-gaap_PatentsMember_738" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_737" xlink:to="Locator_us-gaap_PatentsMember_738" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_731" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="Locator_us-gaap_TradeNamesMember_732" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_731" xlink:to="Locator_us-gaap_TradeNamesMember_732" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_729" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="Locator_us-gaap_DevelopedTechnologyRightsMember_730" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_729" xlink:to="Locator_us-gaap_DevelopedTechnologyRightsMember_730" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_733" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="Locator_us-gaap_CustomerRelationshipsMember_734" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_733" xlink:to="Locator_us-gaap_CustomerRelationshipsMember_734" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_735" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InProcessResearchAndDevelopmentMember" xlink:label="Locator_us-gaap_InProcessResearchAndDevelopmentMember_736" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_735" xlink:to="Locator_us-gaap_InProcessResearchAndDevelopmentMember_736" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_705" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="Locator_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_706" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_705" xlink:to="Locator_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_706" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="Locator_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_725" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_726" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_725" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_726" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_739" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsGross_740" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_739" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsGross_740" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_741" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_742" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_741" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_742" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_743" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetUsefulLife_744" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsLineItems_743" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetUsefulLife_744" order="3.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/AcquisitionsNarrativesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_835" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionEffectiveDateOfAcquisition1" xlink:label="Locator_us-gaap_BusinessAcquisitionEffectiveDateOfAcquisition1_836" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_835" xlink:to="Locator_us-gaap_BusinessAcquisitionEffectiveDateOfAcquisition1_836" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_837" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="Locator_us-gaap_BusinessCombinationConsiderationTransferred1_838" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_837" xlink:to="Locator_us-gaap_BusinessCombinationConsiderationTransferred1_838" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_839" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity" xlink:label="Locator_us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity_840" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_839" xlink:to="Locator_us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity_840" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_841" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetUsefulLife_842" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_841" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetUsefulLife_842" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_843" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts" xlink:label="Locator_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_844" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_843" xlink:to="Locator_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_844" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_845" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NumberOfBusinessesAcquired" xlink:label="Locator_us-gaap_NumberOfBusinessesAcquired_846" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_845" xlink:to="Locator_us-gaap_NumberOfBusinessesAcquired_846" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_847" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:label="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_848" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_847" xlink:to="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_848" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:label="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_849" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:label="Locator_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_850" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_849" xlink:to="Locator_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_850" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:label="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_851" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:label="Locator_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_852" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_851" xlink:to="Locator_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_852" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:label="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_853" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusniessCombinationPurchaseAccountingInventoryFairValueStepUpAmortization" xlink:label="Locator_hbio_BusniessCombinationPurchaseAccountingInventoryFairValueStepUpAmortization_854" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_853" xlink:to="Locator_hbio_BusniessCombinationPurchaseAccountingInventoryFairValueStepUpAmortization_854" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:label="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_855" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_PreliminaryAmountOfInventoryFairValueStepUp" xlink:label="Locator_hbio_PreliminaryAmountOfInventoryFairValueStepUp_856" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_855" xlink:to="Locator_hbio_PreliminaryAmountOfInventoryFairValueStepUp_856" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:label="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_857" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_AmortizationPeriodOfPurchaseAccountingInventoryFairValueStepUpAmortization" xlink:label="Locator_hbio_AmortizationPeriodOfPurchaseAccountingInventoryFairValueStepUpAmortization_858" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_857" xlink:to="Locator_hbio_AmortizationPeriodOfPurchaseAccountingInventoryFairValueStepUpAmortization_858" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationAbstract" xlink:label="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_859" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationProformaInformationAmortizationOfIntangibleAsets" xlink:label="Locator_hbio_BusinessCombinationProformaInformationAmortizationOfIntangibleAsets_860" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionProFormaInformationAbstract_859" xlink:to="Locator_hbio_BusinessCombinationProformaInformationAmortizationOfIntangibleAsets_860" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_861" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_862" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_861" xlink:to="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_862" order="8.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_863" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentFinancialLiabilities" xlink:label="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentFinancialLiabilities_864" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_863" xlink:to="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentFinancialLiabilities_864" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_865" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredLiabilties" xlink:label="Locator_hbio_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredLiabilties_866" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_865" xlink:to="Locator_hbio_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredLiabilties_866" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_867" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentWorkingCapital" xlink:label="Locator_hbio_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentWorkingCapital_868" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_867" xlink:to="Locator_hbio_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentWorkingCapital_868" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_869" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:label="Locator_us-gaap_GoodwillPurchaseAccountingAdjustments_870" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_869" xlink:to="Locator_us-gaap_GoodwillPurchaseAccountingAdjustments_870" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_793" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_794" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_793" xlink:to="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_794" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_817" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_818" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_817" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_818" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_821" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_822" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_821" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_822" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_823" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="Locator_us-gaap_TradeNamesMember_824" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_823" xlink:to="Locator_us-gaap_TradeNamesMember_824" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_825" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="Locator_us-gaap_DevelopedTechnologyRightsMember_826" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_825" xlink:to="Locator_us-gaap_DevelopedTechnologyRightsMember_826" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_827" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="Locator_us-gaap_CustomerRelationshipsMember_828" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_827" xlink:to="Locator_us-gaap_CustomerRelationshipsMember_828" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_829" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InProcessResearchAndDevelopmentMember" xlink:label="Locator_us-gaap_InProcessResearchAndDevelopmentMember_830" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_829" xlink:to="Locator_us-gaap_InProcessResearchAndDevelopmentMember_830" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_819" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="Locator_us-gaap_BusinessAcquisitionAxis_820" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_819" xlink:to="Locator_us-gaap_BusinessAcquisitionAxis_820" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="Locator_us-gaap_BusinessAcquisitionAxis_831" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_832" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_BusinessAcquisitionAxis_831" xlink:to="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_832" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_833" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember" xlink:label="Locator_us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember_834" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_833" xlink:to="Locator_us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember_834" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/AcquisitionsDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_993" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_994" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_993" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_994" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_995" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTangibleAssets" xlink:label="Locator_hbio_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTangibleAssets_996" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_995" xlink:to="Locator_hbio_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedTangibleAssets_996" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_997" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_998" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_997" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_998" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_999" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationRecognizedIdentifiableNetAssets" xlink:label="Locator_hbio_BusinessCombinationRecognizedIdentifiableNetAssets_1000" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_999" xlink:to="Locator_hbio_BusinessCombinationRecognizedIdentifiableNetAssets_1000" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_1001" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract" xlink:label="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1002" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_1001" xlink:to="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1002" order="4.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract" xlink:label="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1003" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="Locator_us-gaap_Goodwill_1004" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1003" xlink:to="Locator_us-gaap_Goodwill_1004" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract" xlink:label="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1005" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_1006" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1005" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_1006" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract" xlink:label="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1007" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilitiesCurrent" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilitiesCurrent_1008" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1007" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilitiesCurrent_1008" order="3.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract" xlink:label="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1009" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BusinessCombinationRecognizedGoodwillAndIntangibleAssetsNetOfTax" xlink:label="Locator_hbio_BusinessCombinationRecognizedGoodwillAndIntangibleAssetsNetOfTax_1010" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_BusinessCombinationGoodwillAndIntangibleAssetsAbstract_1009" xlink:to="Locator_hbio_BusinessCombinationRecognizedGoodwillAndIntangibleAssetsNetOfTax_1010" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_1011" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_1012" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_1011" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_1012" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_1013" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1014" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_1013" xlink:to="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1014" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1015" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_1016" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1015" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_1016" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1017" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_1018" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1017" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_1018" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1019" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_1020" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1019" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_1020" order="3.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1021" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_1022" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1021" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_1022" order="4.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1023" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_1024" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1023" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_1024" order="5.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1025" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets_1026" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1025" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets_1026" order="6.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1027" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_1028" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1027" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_1028" order="8.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1029" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_1030" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1029" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_1030" order="9.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract" xlink:label="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1031" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:label="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_1032" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TangibleAssetsAndLiabilitiesAssumedAsReferencedAbovePreliminarilyConsistOfTheFollowingAbstract_1031" xlink:to="Locator_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_1032" order="10.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_1033" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:label="Locator_us-gaap_BusinessAcquisitionsProFormaRevenue_1034" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_1033" xlink:to="Locator_us-gaap_BusinessAcquisitionsProFormaRevenue_1034" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_1035" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:label="Locator_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_1036" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_1035" xlink:to="Locator_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_1036" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_899" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_900" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_899" xlink:to="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_900" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_975" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_976" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_975" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_976" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_979" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_980" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_979" xlink:to="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_980" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_981" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="Locator_us-gaap_TradeNamesMember_982" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_981" xlink:to="Locator_us-gaap_TradeNamesMember_982" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_983" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DevelopedTechnologyRightsMember" xlink:label="Locator_us-gaap_DevelopedTechnologyRightsMember_984" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_983" xlink:to="Locator_us-gaap_DevelopedTechnologyRightsMember_984" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_985" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="Locator_us-gaap_CustomerRelationshipsMember_986" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_985" xlink:to="Locator_us-gaap_CustomerRelationshipsMember_986" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_987" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InProcessResearchAndDevelopmentMember" xlink:label="Locator_us-gaap_InProcessResearchAndDevelopmentMember_988" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_987" xlink:to="Locator_us-gaap_InProcessResearchAndDevelopmentMember_988" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_977" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="Locator_us-gaap_BusinessAcquisitionAxis_978" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_977" xlink:to="Locator_us-gaap_BusinessAcquisitionAxis_978" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="Locator_us-gaap_BusinessAcquisitionAxis_989" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_990" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_BusinessAcquisitionAxis_989" xlink:to="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_990" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_991" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember" xlink:label="Locator_us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember_992" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_991" xlink:to="Locator_us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember_992" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/CapitalStockNarrativesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1365" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1366" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1365" xlink:to="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1366" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1367" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="Locator_us-gaap_CommonStockSharesAuthorized_1368" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1367" xlink:to="Locator_us-gaap_CommonStockSharesAuthorized_1368" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1369" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="Locator_us-gaap_CommonStockSharesIssued_1370" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1369" xlink:to="Locator_us-gaap_CommonStockSharesIssued_1370" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1371" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="Locator_us-gaap_CommonStockSharesOutstanding_1372" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1371" xlink:to="Locator_us-gaap_CommonStockSharesOutstanding_1372" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1373" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1374" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1373" xlink:to="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1374" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1375" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConvertiblePreferredStockTermsOfConversion" xlink:label="Locator_us-gaap_ConvertiblePreferredStockTermsOfConversion_1376" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1375" xlink:to="Locator_us-gaap_ConvertiblePreferredStockTermsOfConversion_1376" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1377" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="Locator_us-gaap_PreferredStockSharesOutstanding_1378" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1377" xlink:to="Locator_us-gaap_PreferredStockSharesOutstanding_1378" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1379" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_PreferredStockPurchaseRightOptionExercised" xlink:label="Locator_hbio_PreferredStockPurchaseRightOptionExercised_1380" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1379" xlink:to="Locator_hbio_PreferredStockPurchaseRightOptionExercised_1380" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1381" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DateOfStockRepurchaseProgramAuthorized" xlink:label="Locator_hbio_DateOfStockRepurchaseProgramAuthorized_1382" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1381" xlink:to="Locator_hbio_DateOfStockRepurchaseProgramAuthorized_1382" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1383" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="Locator_us-gaap_PreferredStockSharesAuthorized_1384" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_1383" xlink:to="Locator_us-gaap_PreferredStockSharesAuthorized_1384" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1385" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="Locator_us-gaap_StockRepurchaseProgramAuthorizedAmount1_1386" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1385" xlink:to="Locator_us-gaap_StockRepurchaseProgramAuthorizedAmount1_1386" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1387" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract" xlink:label="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1388" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1387" xlink:to="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1388" order="4.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract" xlink:label="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1389" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP" xlink:label="Locator_us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP_1390" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1389" xlink:to="Locator_us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP_1390" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract" xlink:label="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1391" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_EmployeeStockPurchasePlanSharesAuthorized" xlink:label="Locator_hbio_EmployeeStockPurchasePlanSharesAuthorized_1392" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1391" xlink:to="Locator_hbio_EmployeeStockPurchasePlanSharesAuthorized_1392" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract" xlink:label="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1393" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate_1394" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_EmployeeStockPurchasePlanAsAmendedTheEsppAbstract_1393" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate_1394" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1395" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchaseProgramPeriodInForce1" xlink:label="Locator_us-gaap_StockRepurchaseProgramPeriodInForce1_1396" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1395" xlink:to="Locator_us-gaap_StockRepurchaseProgramPeriodInForce1_1396" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1397" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="Locator_us-gaap_TreasuryStockSharesAcquired_1398" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1397" xlink:to="Locator_us-gaap_TreasuryStockSharesAcquired_1398" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1399" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="Locator_us-gaap_TreasuryStockValueAcquiredCostMethod_1400" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1399" xlink:to="Locator_us-gaap_TreasuryStockValueAcquiredCostMethod_1400" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1401" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TreasuryStockAcquiredUnderStockRepurchaseProgram" xlink:label="Locator_hbio_TreasuryStockAcquiredUnderStockRepurchaseProgram_1402" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1401" xlink:to="Locator_hbio_TreasuryStockAcquiredUnderStockRepurchaseProgram_1402" order="8.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1403" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TreasuryStockNumberOfSharesAcquiredUnderStockRepurchaseProgram" xlink:label="Locator_hbio_TreasuryStockNumberOfSharesAcquiredUnderStockRepurchaseProgram_1404" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1403" xlink:to="Locator_hbio_TreasuryStockNumberOfSharesAcquiredUnderStockRepurchaseProgram_1404" order="9.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1405" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_1406" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1405" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_1406" order="10.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1407" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DateOfAmendmentOfStockOptionAndIncentivePlanByBoardOfDirectors" xlink:label="Locator_hbio_DateOfAmendmentOfStockOptionAndIncentivePlanByBoardOfDirectors_1408" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1407" xlink:to="Locator_hbio_DateOfAmendmentOfStockOptionAndIncentivePlanByBoardOfDirectors_1408" order="11.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1409" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_1410" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1409" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_1410" order="12.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1411" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncreaseInNumberOfSharesAuthorizedForIssuanceUnderStockOptionAndIncentivePlan" xlink:label="Locator_hbio_IncreaseInNumberOfSharesAuthorizedForIssuanceUnderStockOptionAndIncentivePlan_1412" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1411" xlink:to="Locator_hbio_IncreaseInNumberOfSharesAuthorizedForIssuanceUnderStockOptionAndIncentivePlan_1412" order="13.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1413" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_LimitationOfNumberOfAwardsThatCanBeIssuedUnderStockOptionAndIncentivePlan" xlink:label="Locator_hbio_LimitationOfNumberOfAwardsThatCanBeIssuedUnderStockOptionAndIncentivePlan_1414" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1413" xlink:to="Locator_hbio_LimitationOfNumberOfAwardsThatCanBeIssuedUnderStockOptionAndIncentivePlan_1414" order="14.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1415" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FungibleSharesIssuanceRatio" xlink:label="Locator_hbio_FungibleSharesIssuanceRatio_1416" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1415" xlink:to="Locator_hbio_FungibleSharesIssuanceRatio_1416" order="15.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1419" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_1420" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1419" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_1420" order="17.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1421" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualMaximumContractualTerm1" xlink:label="Locator_us-gaap_DeferredCompensationArrangementWithIndividualMaximumContractualTerm1_1422" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1421" xlink:to="Locator_us-gaap_DeferredCompensationArrangementWithIndividualMaximumContractualTerm1_1422" order="18.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1423" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="Locator_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1424" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1423" xlink:to="Locator_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1424" order="19.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1425" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount" xlink:label="Locator_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_1426" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1425" xlink:to="Locator_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount_1426" order="20.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1427" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_PercentageOfOutstandingCommonStock" xlink:label="Locator_hbio_PercentageOfOutstandingCommonStock_1428" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1427" xlink:to="Locator_hbio_PercentageOfOutstandingCommonStock_1428" order="21.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1429" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_SharesAuthorizedForIssuanceUnder1996StockOptionAndIncentivePlan" xlink:label="Locator_hbio_SharesAuthorizedForIssuanceUnder1996StockOptionAndIncentivePlan_1430" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1429" xlink:to="Locator_hbio_SharesAuthorizedForIssuanceUnder1996StockOptionAndIncentivePlan_1430" order="22.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1431" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesHeldInEmployeeStockOptionPlanSuspenseShares" xlink:label="Locator_us-gaap_SharesHeldInEmployeeStockOptionPlanSuspenseShares_1432" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1431" xlink:to="Locator_us-gaap_SharesHeldInEmployeeStockOptionPlanSuspenseShares_1432" order="23.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1433" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_RestrictedStockUnitsOutstandingForIssuanceOfAwards" xlink:label="Locator_hbio_RestrictedStockUnitsOutstandingForIssuanceOfAwards_1434" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1433" xlink:to="Locator_hbio_RestrictedStockUnitsOutstandingForIssuanceOfAwards_1434" order="24.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1435" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncentiveStockOptionsGrantedToDate" xlink:label="Locator_hbio_IncentiveStockOptionsGrantedToDate_1436" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1435" xlink:to="Locator_hbio_IncentiveStockOptionsGrantedToDate_1436" order="25.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1437" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_NonQualifiedStockOptionsGrantedToDate" xlink:label="Locator_hbio_NonQualifiedStockOptionsGrantedToDate_1438" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1437" xlink:to="Locator_hbio_NonQualifiedStockOptionsGrantedToDate_1438" order="26.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1439" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CommonStockMarketValuePerShareOnReportingDate" xlink:label="Locator_hbio_CommonStockMarketValuePerShareOnReportingDate_1440" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1439" xlink:to="Locator_hbio_CommonStockMarketValuePerShareOnReportingDate_1440" order="27.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1441" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_1442" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1441" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_1442" order="28.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1443" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_InTheMoneyStockOptionsExercisableAtTheReportingDate" xlink:label="Locator_hbio_InTheMoneyStockOptionsExercisableAtTheReportingDate_1444" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1443" xlink:to="Locator_hbio_InTheMoneyStockOptionsExercisableAtTheReportingDate_1444" order="29.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1445" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="Locator_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1446" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1445" xlink:to="Locator_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1446" order="30.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1447" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_AnnualizedEstimatedForfeitureRate" xlink:label="Locator_hbio_AnnualizedEstimatedForfeitureRate_1448" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1447" xlink:to="Locator_hbio_AnnualizedEstimatedForfeitureRate_1448" order="31.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1449" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_WeightedAverageEstimatedBlackScholesValueOfOptionGrants" xlink:label="Locator_hbio_WeightedAverageEstimatedBlackScholesValueOfOptionGrants_1450" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1449" xlink:to="Locator_hbio_WeightedAverageEstimatedBlackScholesValueOfOptionGrants_1450" order="32.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1451" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncrementalOptionsGrantedDueToHartSpinoff" xlink:label="Locator_hbio_IncrementalOptionsGrantedDueToHartSpinoff_1452" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1451" xlink:to="Locator_hbio_IncrementalOptionsGrantedDueToHartSpinoff_1452" order="33.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1453" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncrementalUnitsGrantedDueToHartSpinoff" xlink:label="Locator_hbio_IncrementalUnitsGrantedDueToHartSpinoff_1454" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1453" xlink:to="Locator_hbio_IncrementalUnitsGrantedDueToHartSpinoff_1454" order="34.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1455" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_1456" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1455" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_1456" order="35.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1457" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost_1458" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1457" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost_1458" order="36.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1459" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CumulativeEffectOnRetainedEarningsBeforeTax1" xlink:label="Locator_us-gaap_CumulativeEffectOnRetainedEarningsBeforeTax1_1460" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1459" xlink:to="Locator_us-gaap_CumulativeEffectOnRetainedEarningsBeforeTax1_1460" order="37.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1461" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MaximumPercentageOfTargetNumberOfRestrictedStockUnits" xlink:label="Locator_hbio_MaximumPercentageOfTargetNumberOfRestrictedStockUnits_1462" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1461" xlink:to="Locator_hbio_MaximumPercentageOfTargetNumberOfRestrictedStockUnits_1462" order="38.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1463" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="Locator_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_1464" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1463" xlink:to="Locator_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_1464" order="39.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1465" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1466" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1465" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1466" order="40.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1467" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:label="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_1468" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1467" xlink:to="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_1468" order="41.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1469" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1470" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1469" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1470" order="42.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1417" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_1418" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1417" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_1418" order="16.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1317" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1318" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1317" xlink:to="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1318" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1343" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="Locator_srt_RangeAxis_1344" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1343" xlink:to="Locator_srt_RangeAxis_1344" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="Locator_srt_RangeAxis_1347" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="Locator_srt_RangeMember_1348" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_srt_RangeAxis_1347" xlink:to="Locator_srt_RangeMember_1348" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="Locator_srt_RangeAxis_1473" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="Locator_srt_RangeMember_1474" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_srt_RangeAxis_1473" xlink:to="Locator_srt_RangeMember_1474" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="Locator_srt_RangeMember_1349" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="Locator_srt_MinimumMember_1350" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_RangeMember_1349" xlink:to="Locator_srt_MinimumMember_1350" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="Locator_srt_RangeMember_1351" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="Locator_srt_MaximumMember_1352" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_RangeMember_1351" xlink:to="Locator_srt_MaximumMember_1352" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1345" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="Locator_us-gaap_AwardTypeAxis_1346" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1345" xlink:to="Locator_us-gaap_AwardTypeAxis_1346" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="Locator_us-gaap_AwardTypeAxis_1353" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1354" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_AwardTypeAxis_1353" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1354" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="Locator_us-gaap_AwardTypeAxis_1471" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1472" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_AwardTypeAxis_1471" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1472" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1357" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MarketCondition2018RsusMemberMember" xlink:label="Locator_hbio_MarketCondition2018RsusMemberMember_1358" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1357" xlink:to="Locator_hbio_MarketCondition2018RsusMemberMember_1358" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1359" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MarketCondition2019RsusMember" xlink:label="Locator_hbio_MarketCondition2019RsusMember_1360" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1359" xlink:to="Locator_hbio_MarketCondition2019RsusMember_1360" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1361" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DeferredStockAwardsOfMarketConditionRsuApprovedAug2015Member" xlink:label="Locator_hbio_DeferredStockAwardsOfMarketConditionRsuApprovedAug2015Member_1362" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1361" xlink:to="Locator_hbio_DeferredStockAwardsOfMarketConditionRsuApprovedAug2015Member_1362" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1363" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DeferredStockAwardsOfMarketConditionRsuApprovedMay2018Member" xlink:label="Locator_hbio_DeferredStockAwardsOfMarketConditionRsuApprovedMay2018Member_1364" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1363" xlink:to="Locator_hbio_DeferredStockAwardsOfMarketConditionRsuApprovedMay2018Member_1364" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1355" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MarketConditionRestrictedStockUnitMember" xlink:label="Locator_hbio_MarketConditionRestrictedStockUnitMember_1356" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1355" xlink:to="Locator_hbio_MarketConditionRestrictedStockUnitMember_1356" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/CapitalStockStockOptionsAndRestrictedStockActivityDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1571" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_1572" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1571" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_1572" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1573" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_1574" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1573" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_1574" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1575" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_StockOptionsAndRestrictedStockUnitsIssued" xlink:label="Locator_hbio_StockOptionsAndRestrictedStockUnitsIssued_1576" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1575" xlink:to="Locator_hbio_StockOptionsAndRestrictedStockUnitsIssued_1576" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1577" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1578" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1577" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1578" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1579" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1580" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1579" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1580" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1581" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_1582" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1581" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_1582" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1583" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_1584" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1583" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_1584" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1585" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="Locator_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_1586" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1585" xlink:to="Locator_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_1586" order="9.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1587" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_1588" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1587" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_1588" order="10.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1589" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_1590" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1589" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_1590" order="11.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1591" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_1592" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1591" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_1592" order="12.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1593" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_1594" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1593" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_1594" order="13.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1595" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FungibleShareAdjustmentForRestrictedStockUnitsGranted" xlink:label="Locator_hbio_FungibleShareAdjustmentForRestrictedStockUnitsGranted_1596" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1595" xlink:to="Locator_hbio_FungibleShareAdjustmentForRestrictedStockUnitsGranted_1596" order="15.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1597" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:label="Locator_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_1598" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1597" xlink:to="Locator_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_1598" order="16.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1599" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1600" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1599" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1600" order="18.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1601" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_1602" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1601" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_1602" order="19.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1603" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_1604" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1603" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_1604" order="20.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1605" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1606" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1605" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_1606" order="21.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1607" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1608" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1607" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1608" order="23.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1609" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1610" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1609" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1610" order="24.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1611" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue" xlink:label="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_1612" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1611" xlink:to="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_1612" order="25.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1613" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_1614" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1613" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_1614" order="26.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1615" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ShareOptionsAndRestrictedStockUnitsForfeituresAndExpirationsInPeriod" xlink:label="Locator_hbio_ShareOptionsAndRestrictedStockUnitsForfeituresAndExpirationsInPeriod_1616" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1615" xlink:to="Locator_hbio_ShareOptionsAndRestrictedStockUnitsForfeituresAndExpirationsInPeriod_1616" order="28.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1617" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_StockOptionsAndRestrictedStockUnitsCancelled" xlink:label="Locator_hbio_StockOptionsAndRestrictedStockUnitsCancelled_1618" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1617" xlink:to="Locator_hbio_StockOptionsAndRestrictedStockUnitsCancelled_1618" order="29.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1619" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FungibleShareAdjustmentForRestrictedStockUnitsCancelled" xlink:label="Locator_hbio_FungibleShareAdjustmentForRestrictedStockUnitsCancelled_1620" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1619" xlink:to="Locator_hbio_FungibleShareAdjustmentForRestrictedStockUnitsCancelled_1620" order="30.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1621" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_StockIssuedDuringPeriodGrossStockOptionsExercised" xlink:label="Locator_hbio_StockIssuedDuringPeriodGrossStockOptionsExercised_1622" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1621" xlink:to="Locator_hbio_StockIssuedDuringPeriodGrossStockOptionsExercised_1622" order="31.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1561" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1562" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1561" xlink:to="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1562" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1565" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="Locator_us-gaap_AwardTypeAxis_1566" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1565" xlink:to="Locator_us-gaap_AwardTypeAxis_1566" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="Locator_us-gaap_AwardTypeAxis_1567" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1568" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_AwardTypeAxis_1567" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1568" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1569" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MarketConditionRestrictedStockUnitMember" xlink:label="Locator_hbio_MarketConditionRestrictedStockUnitMember_1570" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1569" xlink:to="Locator_hbio_MarketConditionRestrictedStockUnitMember_1570" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/LongTermDebtNarrativesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1711" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_PreviousApprovedCreditFacility" xlink:label="Locator_hbio_PreviousApprovedCreditFacility_1712" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1711" xlink:to="Locator_hbio_PreviousApprovedCreditFacility_1712" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1715" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="Locator_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_1716" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1715" xlink:to="Locator_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_1716" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1717" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="Locator_us-gaap_ProceedsFromLinesOfCredit_1718" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1717" xlink:to="Locator_us-gaap_ProceedsFromLinesOfCredit_1718" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1719" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="Locator_us-gaap_DebtInstrumentTerm_1720" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1719" xlink:to="Locator_us-gaap_DebtInstrumentTerm_1720" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1721" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="Locator_us-gaap_DebtInstrumentMaturityDate_1722" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1721" xlink:to="Locator_us-gaap_DebtInstrumentMaturityDate_1722" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1723" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentPaymentTerms" xlink:label="Locator_us-gaap_DebtInstrumentPaymentTerms_1724" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1723" xlink:to="Locator_us-gaap_DebtInstrumentPaymentTerms_1724" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1725" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DebtInstrumentQuarterlyPaymentCurrentYear" xlink:label="Locator_hbio_DebtInstrumentQuarterlyPaymentCurrentYear_1726" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1725" xlink:to="Locator_hbio_DebtInstrumentQuarterlyPaymentCurrentYear_1726" order="8.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1727" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DebtInstrumentQuarterlyPaymentNextYear" xlink:label="Locator_hbio_DebtInstrumentQuarterlyPaymentNextYear_1728" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1727" xlink:to="Locator_hbio_DebtInstrumentQuarterlyPaymentNextYear_1728" order="9.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1729" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DebtInstrumentQuarterlyPaymentThereafter" xlink:label="Locator_hbio_DebtInstrumentQuarterlyPaymentThereafter_1730" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1729" xlink:to="Locator_hbio_DebtInstrumentQuarterlyPaymentThereafter_1730" order="10.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1731" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_LimitationOnPledgesOfCapitalStockOfForeignSubsidiaries" xlink:label="Locator_hbio_LimitationOnPledgesOfCapitalStockOfForeignSubsidiaries_1732" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1731" xlink:to="Locator_hbio_LimitationOnPledgesOfCapitalStockOfForeignSubsidiaries_1732" order="11.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1733" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xlink:label="Locator_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis_1734" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1733" xlink:to="Locator_us-gaap_DebtInstrumentDescriptionOfVariableRateBasis_1734" order="12.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1735" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="Locator_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_1736" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1735" xlink:to="Locator_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_1736" order="13.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1737" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFloorInterestRate" xlink:label="Locator_us-gaap_DerivativeFloorInterestRate_1738" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1737" xlink:to="Locator_us-gaap_DerivativeFloorInterestRate_1738" order="14.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1739" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MinimunPercentageOfTermLoanAndDelayedDrawTermLoanOnWhichInterestRateRequiredToBeFixed" xlink:label="Locator_hbio_MinimunPercentageOfTermLoanAndDelayedDrawTermLoanOnWhichInterestRateRequiredToBeFixed_1740" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1739" xlink:to="Locator_hbio_MinimunPercentageOfTermLoanAndDelayedDrawTermLoanOnWhichInterestRateRequiredToBeFixed_1740" order="15.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1741" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCredit" xlink:label="Locator_us-gaap_LineOfCredit_1742" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1741" xlink:to="Locator_us-gaap_LineOfCredit_1742" order="16.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1743" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="Locator_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_1744" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1743" xlink:to="Locator_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_1744" order="17.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1745" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_PercentageOfConsoildatedExcessCashFlowForMandatoryPrepaymentObligation" xlink:label="Locator_hbio_PercentageOfConsoildatedExcessCashFlowForMandatoryPrepaymentObligation_1746" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1745" xlink:to="Locator_hbio_PercentageOfConsoildatedExcessCashFlowForMandatoryPrepaymentObligation_1746" order="18.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1747" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarlyRepaymentOfSeniorDebt" xlink:label="Locator_us-gaap_EarlyRepaymentOfSeniorDebt_1748" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1747" xlink:to="Locator_us-gaap_EarlyRepaymentOfSeniorDebt_1748" order="19.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1749" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_LimitationOnPledgesOfCapitalStockOfForeignSubsidiariesPercentage" xlink:label="Locator_hbio_LimitationOnPledgesOfCapitalStockOfForeignSubsidiariesPercentage_1750" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1749" xlink:to="Locator_hbio_LimitationOnPledgesOfCapitalStockOfForeignSubsidiariesPercentage_1750" order="20.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1751" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_InterestRateInExcessOfLiborOnCreditFacility" xlink:label="Locator_hbio_InterestRateInExcessOfLiborOnCreditFacility_1752" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1751" xlink:to="Locator_hbio_InterestRateInExcessOfLiborOnCreditFacility_1752" order="21.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1753" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_SecuredDebtInterestRateAtPeriodEnd" xlink:label="Locator_hbio_SecuredDebtInterestRateAtPeriodEnd_1754" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1753" xlink:to="Locator_hbio_SecuredDebtInterestRateAtPeriodEnd_1754" order="22.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1755" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_LiborFixedRate" xlink:label="Locator_hbio_LiborFixedRate_1756" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1755" xlink:to="Locator_hbio_LiborFixedRate_1756" order="23.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1757" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:label="Locator_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod_1758" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1757" xlink:to="Locator_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod_1758" order="24.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1759" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:label="Locator_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_1760" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1759" xlink:to="Locator_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_1760" order="25.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1761" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DdtlThresholdForDollarForDollarReductionInRevolvingLine" xlink:label="Locator_hbio_DdtlThresholdForDollarForDollarReductionInRevolvingLine_1762" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1761" xlink:to="Locator_hbio_DdtlThresholdForDollarForDollarReductionInRevolvingLine_1762" order="26.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1763" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TransferofDelayedDrawDownTermLoanCapacityToRevolverCapacity" xlink:label="Locator_hbio_TransferofDelayedDrawDownTermLoanCapacityToRevolverCapacity_1764" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1763" xlink:to="Locator_hbio_TransferofDelayedDrawDownTermLoanCapacityToRevolverCapacity_1764" order="27.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1687" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="Locator_us-gaap_DebtInstrumentTable_1688" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1687" xlink:to="Locator_us-gaap_DebtInstrumentTable_1688" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="Locator_us-gaap_DebtInstrumentTable_1691" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="Locator_us-gaap_VariableRateAxis_1692" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DebtInstrumentTable_1691" xlink:to="Locator_us-gaap_VariableRateAxis_1692" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="Locator_us-gaap_VariableRateAxis_1703" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="Locator_us-gaap_VariableRateDomain_1704" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_VariableRateAxis_1703" xlink:to="Locator_us-gaap_VariableRateDomain_1704" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="Locator_us-gaap_VariableRateAxis_1767" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="Locator_us-gaap_VariableRateDomain_1768" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_VariableRateAxis_1767" xlink:to="Locator_us-gaap_VariableRateDomain_1768" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="Locator_us-gaap_VariableRateDomain_1707" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BaseRateMember" xlink:label="Locator_us-gaap_BaseRateMember_1708" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_VariableRateDomain_1707" xlink:to="Locator_us-gaap_BaseRateMember_1708" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="Locator_us-gaap_VariableRateDomain_1709" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="Locator_us-gaap_LondonInterbankOfferedRateLIBORMember_1710" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_VariableRateDomain_1709" xlink:to="Locator_us-gaap_LondonInterbankOfferedRateLIBORMember_1710" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="Locator_us-gaap_DebtInstrumentTable_1689" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="Locator_us-gaap_LongtermDebtTypeAxis_1690" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DebtInstrumentTable_1689" xlink:to="Locator_us-gaap_LongtermDebtTypeAxis_1690" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="Locator_us-gaap_LongtermDebtTypeAxis_1705" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_1706" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_LongtermDebtTypeAxis_1705" xlink:to="Locator_us-gaap_LongtermDebtTypeDomain_1706" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="Locator_us-gaap_LongtermDebtTypeAxis_1765" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_1766" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_LongtermDebtTypeAxis_1765" xlink:to="Locator_us-gaap_LongtermDebtTypeDomain_1766" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_1693" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="Locator_us-gaap_RevolvingCreditFacilityMember_1694" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_LongtermDebtTypeDomain_1693" xlink:to="Locator_us-gaap_RevolvingCreditFacilityMember_1694" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_1695" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="Locator_us-gaap_SecuredDebtMember_1696" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_LongtermDebtTypeDomain_1695" xlink:to="Locator_us-gaap_SecuredDebtMember_1696" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_1697" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DelayedDrawdownTermLoanMember" xlink:label="Locator_hbio_DelayedDrawdownTermLoanMember_1698" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_LongtermDebtTypeDomain_1697" xlink:to="Locator_hbio_DelayedDrawdownTermLoanMember_1698" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_1699" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ExcessCashFlowMember" xlink:label="Locator_hbio_ExcessCashFlowMember_1700" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_LongtermDebtTypeDomain_1699" xlink:to="Locator_hbio_ExcessCashFlowMember_1700" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_1701" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DenvilleTransactionMember" xlink:label="Locator_hbio_DenvilleTransactionMember_1702" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_LongtermDebtTypeDomain_1701" xlink:to="Locator_hbio_DenvilleTransactionMember_1702" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_1713" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebt" xlink:label="Locator_us-gaap_SecuredDebt_1714" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_1713" xlink:to="Locator_us-gaap_SecuredDebt_1714" order="2.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/IncomeTaxNarrativesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="Locator_us-gaap_IncomeStatementLocationAxis_1893" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_1894" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_IncomeStatementLocationAxis_1893" xlink:to="Locator_us-gaap_IncomeStatementLocationDomain_1894" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_1895" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="Locator_us-gaap_ResearchAndDevelopmentExpenseMember_1896" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeStatementLocationDomain_1895" xlink:to="Locator_us-gaap_ResearchAndDevelopmentExpenseMember_1896" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1923" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="Locator_us-gaap_UnrecognizedTaxBenefits_1924" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1923" xlink:to="Locator_us-gaap_UnrecognizedTaxBenefits_1924" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1925" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="Locator_us-gaap_DeferredTaxAssetsValuationAllowance_1926" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1925" xlink:to="Locator_us-gaap_DeferredTaxAssetsValuationAllowance_1926" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1927" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CumulativeEffectOnRetainedEarningsBeforeTax1" xlink:label="Locator_us-gaap_CumulativeEffectOnRetainedEarningsBeforeTax1_1928" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1927" xlink:to="Locator_us-gaap_CumulativeEffectOnRetainedEarningsBeforeTax1_1928" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1863" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1864" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_1863" xlink:to="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1864" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1873" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1874" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1873" xlink:to="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1874" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1905" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_1906" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1905" xlink:to="Locator_us-gaap_TypeOfAdoptionMember_1906" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_1907" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201609Member" xlink:label="Locator_us-gaap_AccountingStandardsUpdate201609Member_1908" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TypeOfAdoptionMember_1907" xlink:to="Locator_us-gaap_AccountingStandardsUpdate201609Member_1908" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1855" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable" xlink:label="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1856" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1855" xlink:to="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1856" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable" xlink:label="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1865" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationAxis" xlink:label="Locator_hbio_TaxCreditExpirationAxis_1866" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1865" xlink:to="Locator_hbio_TaxCreditExpirationAxis_1866" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationAxis" xlink:label="Locator_hbio_TaxCreditExpirationAxis_1897" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationDomain" xlink:label="Locator_hbio_TaxCreditExpirationDomain_1898" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_hbio_TaxCreditExpirationAxis_1897" xlink:to="Locator_hbio_TaxCreditExpirationDomain_1898" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationAxis" xlink:label="Locator_hbio_TaxCreditExpirationAxis_1929" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationDomain" xlink:label="Locator_hbio_TaxCreditExpirationDomain_1930" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_hbio_TaxCreditExpirationAxis_1929" xlink:to="Locator_hbio_TaxCreditExpirationDomain_1930" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationDomain" xlink:label="Locator_hbio_TaxCreditExpirationDomain_1899" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpire2017Member" xlink:label="Locator_hbio_TaxCreditExpire2017Member_1900" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TaxCreditExpirationDomain_1899" xlink:to="Locator_hbio_TaxCreditExpire2017Member_1900" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationDomain" xlink:label="Locator_hbio_TaxCreditExpirationDomain_1901" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpire2020Member" xlink:label="Locator_hbio_TaxCreditExpire2020Member_1902" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TaxCreditExpirationDomain_1901" xlink:to="Locator_hbio_TaxCreditExpire2020Member_1902" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpirationDomain" xlink:label="Locator_hbio_TaxCreditExpirationDomain_1903" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditExpire2022Member" xlink:label="Locator_hbio_TaxCreditExpire2022Member_1904" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TaxCreditExpirationDomain_1903" xlink:to="Locator_hbio_TaxCreditExpire2022Member_1904" order="3.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable" xlink:label="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1867" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis" xlink:label="Locator_hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis_1868" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1867" xlink:to="Locator_hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis_1868" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis" xlink:label="Locator_hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis_1875" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TypesOfAcquisitionsDomain" xlink:label="Locator_hbio_TypesOfAcquisitionsDomain_1876" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis_1875" xlink:to="Locator_hbio_TypesOfAcquisitionsDomain_1876" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis" xlink:label="Locator_hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis_1931" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TypesOfAcquisitionsDomain" xlink:label="Locator_hbio_TypesOfAcquisitionsDomain_1932" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_hbio_CashInForeignSubsidiariesUsedForAcquisitionsAxis_1931" xlink:to="Locator_hbio_TypesOfAcquisitionsDomain_1932" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TypesOfAcquisitionsDomain" xlink:label="Locator_hbio_TypesOfAcquisitionsDomain_1877" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CmaAcquisitionMember" xlink:label="Locator_hbio_CmaAcquisitionMember_1878" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TypesOfAcquisitionsDomain_1877" xlink:to="Locator_hbio_CmaAcquisitionMember_1878" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TypesOfAcquisitionsDomain" xlink:label="Locator_hbio_TypesOfAcquisitionsDomain_1879" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_AhnBiotechnologieGmbhAcquisitionMember" xlink:label="Locator_hbio_AhnBiotechnologieGmbhAcquisitionMember_1880" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TypesOfAcquisitionsDomain_1879" xlink:to="Locator_hbio_AhnBiotechnologieGmbhAcquisitionMember_1880" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TypesOfAcquisitionsDomain" xlink:label="Locator_hbio_TypesOfAcquisitionsDomain_1881" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MultiChannelSystemsMcsGmbhMember" xlink:label="Locator_hbio_MultiChannelSystemsMcsGmbhMember_1882" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TypesOfAcquisitionsDomain_1881" xlink:to="Locator_hbio_MultiChannelSystemsMcsGmbhMember_1882" order="3.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TypesOfAcquisitionsDomain" xlink:label="Locator_hbio_TypesOfAcquisitionsDomain_1883" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_HekaElektronikMember" xlink:label="Locator_hbio_HekaElektronikMember_1884" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_TypesOfAcquisitionsDomain_1883" xlink:to="Locator_hbio_HekaElektronikMember_1884" order="4.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable" xlink:label="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1869" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="Locator_us-gaap_IncomeTaxAuthorityAxis_1870" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1869" xlink:to="Locator_us-gaap_IncomeTaxAuthorityAxis_1870" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="Locator_us-gaap_IncomeTaxAuthorityAxis_1885" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="Locator_us-gaap_IncomeTaxAuthorityDomain_1886" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_IncomeTaxAuthorityAxis_1885" xlink:to="Locator_us-gaap_IncomeTaxAuthorityDomain_1886" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="Locator_us-gaap_IncomeTaxAuthorityAxis_1933" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="Locator_us-gaap_IncomeTaxAuthorityDomain_1934" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_IncomeTaxAuthorityAxis_1933" xlink:to="Locator_us-gaap_IncomeTaxAuthorityDomain_1934" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="Locator_us-gaap_IncomeTaxAuthorityDomain_1887" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="Locator_us-gaap_DomesticCountryMember_1888" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeTaxAuthorityDomain_1887" xlink:to="Locator_us-gaap_DomesticCountryMember_1888" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="Locator_us-gaap_IncomeTaxAuthorityDomain_1889" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="Locator_us-gaap_StateAndLocalJurisdictionMember_1890" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeTaxAuthorityDomain_1889" xlink:to="Locator_us-gaap_StateAndLocalJurisdictionMember_1890" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="Locator_us-gaap_IncomeTaxAuthorityDomain_1891" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="Locator_us-gaap_ForeignCountryMember_1892" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeTaxAuthorityDomain_1891" xlink:to="Locator_us-gaap_ForeignCountryMember_1892" order="3.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable" xlink:label="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1871" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="Locator_us-gaap_IncomeStatementLocationAxis_1872" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_hbio_ScheduleOfCashInForeignSubsidiariesUsedForAcqusitionTable_1871" xlink:to="Locator_us-gaap_IncomeStatementLocationAxis_1872" order="4.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1909" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CashHeldInForeignSubsidiariesUsedForAcquisitions" xlink:label="Locator_hbio_CashHeldInForeignSubsidiariesUsedForAcquisitions_1910" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1909" xlink:to="Locator_hbio_CashHeldInForeignSubsidiariesUsedForAcquisitions_1910" order="1.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1911" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxRateReconciliationDeductionsStockOptions" xlink:label="Locator_hbio_IncomeTaxRateReconciliationDeductionsStockOptions_1912" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1911" xlink:to="Locator_hbio_IncomeTaxRateReconciliationDeductionsStockOptions_1912" order="2.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1913" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="Locator_us-gaap_OperatingLossCarryforwards_1914" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1913" xlink:to="Locator_us-gaap_OperatingLossCarryforwards_1914" order="3.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1915" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_OperatingLossCarryforwardsExpirationYear" xlink:label="Locator_hbio_OperatingLossCarryforwardsExpirationYear_1916" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1915" xlink:to="Locator_hbio_OperatingLossCarryforwardsExpirationYear_1916" order="4.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1917" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="Locator_us-gaap_TaxCreditCarryforwardAmount_1918" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1917" xlink:to="Locator_us-gaap_TaxCreditCarryforwardAmount_1918" order="5.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1919" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TaxCreditCarryforwardsExpirationYear" xlink:label="Locator_hbio_TaxCreditCarryforwardsExpirationYear_1920" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1919" xlink:to="Locator_hbio_TaxCreditCarryforwardsExpirationYear_1920" order="6.0" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_IncomeTaxDisclosureLineItems" xlink:label="Locator_hbio_IncomeTaxDisclosureLineItems_1921" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:label="Locator_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_1922" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_hbio_IncomeTaxDisclosureLineItems_1921" xlink:to="Locator_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_1922" order="7.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/CapitalStockStockbasedCompensationExpenseDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="Locator_us-gaap_IncomeStatementLocationAxis_1997" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_1998" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_IncomeStatementLocationAxis_1997" xlink:to="Locator_us-gaap_IncomeStatementLocationDomain_1998" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="Locator_us-gaap_IncomeStatementLocationAxis_2011" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_2012" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_IncomeStatementLocationAxis_2011" xlink:to="Locator_us-gaap_IncomeStatementLocationDomain_2012" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_1999" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="Locator_us-gaap_CostOfSalesMember_2000" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeStatementLocationDomain_1999" xlink:to="Locator_us-gaap_CostOfSalesMember_2000" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_2001" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="Locator_us-gaap_SellingAndMarketingExpenseMember_2002" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeStatementLocationDomain_2001" xlink:to="Locator_us-gaap_SellingAndMarketingExpenseMember_2002" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_2003" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="Locator_us-gaap_GeneralAndAdministrativeExpenseMember_2004" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeStatementLocationDomain_2003" xlink:to="Locator_us-gaap_GeneralAndAdministrativeExpenseMember_2004" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_2005" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="Locator_us-gaap_ResearchAndDevelopmentExpenseMember_2006" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeStatementLocationDomain_2005" xlink:to="Locator_us-gaap_ResearchAndDevelopmentExpenseMember_2006" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_2007" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DiscontinuedOperationsMember" xlink:label="Locator_hbio_DiscontinuedOperationsMember_2008" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeStatementLocationDomain_2007" xlink:to="Locator_hbio_DiscontinuedOperationsMember_2008" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="Locator_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_1991" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="Locator_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1992" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_1991" xlink:to="Locator_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1992" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="Locator_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1995" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="Locator_us-gaap_IncomeStatementLocationAxis_1996" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1995" xlink:to="Locator_us-gaap_IncomeStatementLocationAxis_1996" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="Locator_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_2009" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="Locator_us-gaap_ShareBasedCompensation_2010" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_2009" xlink:to="Locator_us-gaap_ShareBasedCompensation_2010" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/ConcentrationsNarrativesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="Locator_us-gaap_ConcentrationRiskLineItems_2071" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="Locator_us-gaap_ConcentrationRiskTable_2072" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_ConcentrationRiskLineItems_2071" xlink:to="Locator_us-gaap_ConcentrationRiskTable_2072" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="Locator_us-gaap_ConcentrationRiskTable_2075" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="Locator_us-gaap_ConcentrationRiskByBenchmarkAxis_2076" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ConcentrationRiskTable_2075" xlink:to="Locator_us-gaap_ConcentrationRiskByBenchmarkAxis_2076" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="Locator_us-gaap_ConcentrationRiskByBenchmarkAxis_2077" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="Locator_us-gaap_ConcentrationRiskBenchmarkDomain_2078" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_ConcentrationRiskByBenchmarkAxis_2077" xlink:to="Locator_us-gaap_ConcentrationRiskBenchmarkDomain_2078" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="Locator_us-gaap_ConcentrationRiskByBenchmarkAxis_2089" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="Locator_us-gaap_ConcentrationRiskBenchmarkDomain_2090" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_ConcentrationRiskByBenchmarkAxis_2089" xlink:to="Locator_us-gaap_ConcentrationRiskBenchmarkDomain_2090" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="Locator_us-gaap_ConcentrationRiskBenchmarkDomain_2079" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="Locator_us-gaap_AccountsReceivableMember_2080" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ConcentrationRiskBenchmarkDomain_2079" xlink:to="Locator_us-gaap_AccountsReceivableMember_2080" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="Locator_us-gaap_ConcentrationRiskLineItems_2081" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskCustomer" xlink:label="Locator_us-gaap_ConcentrationRiskCustomer_2082" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ConcentrationRiskLineItems_2081" xlink:to="Locator_us-gaap_ConcentrationRiskCustomer_2082" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="Locator_us-gaap_ConcentrationRiskLineItems_2083" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_NumberOfCustomersWithBenchmarkContribution" xlink:label="Locator_hbio_NumberOfCustomersWithBenchmarkContribution_2084" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ConcentrationRiskLineItems_2083" xlink:to="Locator_hbio_NumberOfCustomersWithBenchmarkContribution_2084" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="Locator_us-gaap_ConcentrationRiskLineItems_2085" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="Locator_us-gaap_ConcentrationRiskPercentage1_2086" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ConcentrationRiskLineItems_2085" xlink:to="Locator_us-gaap_ConcentrationRiskPercentage1_2086" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="Locator_us-gaap_ConcentrationRiskLineItems_2087" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_NumberOfCustomersWithBenchmarkContributionExceptOne" xlink:label="Locator_hbio_NumberOfCustomersWithBenchmarkContributionExceptOne_2088" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ConcentrationRiskLineItems_2087" xlink:to="Locator_hbio_NumberOfCustomersWithBenchmarkContributionExceptOne_2088" order="4.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/PropertyPlantAndEquipmentDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2105" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="Locator_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2106" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2105" xlink:to="Locator_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2106" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="Locator_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2113" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2114" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2113" xlink:to="Locator_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2114" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2115" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2116" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2115" xlink:to="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2116" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2135" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2136" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2135" xlink:to="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2136" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2117" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LandBuildingsAndImprovementsMember" xlink:label="Locator_us-gaap_LandBuildingsAndImprovementsMember_2118" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2117" xlink:to="Locator_us-gaap_LandBuildingsAndImprovementsMember_2118" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2119" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="Locator_us-gaap_MachineryAndEquipmentMember_2120" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2119" xlink:to="Locator_us-gaap_MachineryAndEquipmentMember_2120" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2121" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="Locator_us-gaap_ComputerEquipmentMember_2122" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2121" xlink:to="Locator_us-gaap_ComputerEquipmentMember_2122" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2123" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="Locator_us-gaap_FurnitureAndFixturesMember_2124" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2123" xlink:to="Locator_us-gaap_FurnitureAndFixturesMember_2124" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2125" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AutomobilesMember" xlink:label="Locator_us-gaap_AutomobilesMember_2126" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2125" xlink:to="Locator_us-gaap_AutomobilesMember_2126" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2127" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember" xlink:label="Locator_us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember_2128" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentTypeDomain_2127" xlink:to="Locator_us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember_2128" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2129" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentGross_2130" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2129" xlink:to="Locator_us-gaap_PropertyPlantAndEquipmentGross_2130" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2131" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="Locator_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_2132" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2131" xlink:to="Locator_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_2132" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2133" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="Locator_us-gaap_PropertyPlantAndEquipmentNet_2134" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PropertyPlantAndEquipmentLineItems_2133" xlink:to="Locator_us-gaap_PropertyPlantAndEquipmentNet_2134" order="3.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/EmployeeBenefitPlansDefinedBenefitPlanDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2277" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="Locator_us-gaap_FairValueInputsLevel1Member_2278" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2277" xlink:to="Locator_us-gaap_FairValueInputsLevel1Member_2278" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2279" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="Locator_us-gaap_FairValueInputsLevel2Member_2280" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2279" xlink:to="Locator_us-gaap_FairValueInputsLevel2Member_2280" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2281" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="Locator_us-gaap_FairValueInputsLevel3Member_2282" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2281" xlink:to="Locator_us-gaap_FairValueInputsLevel3Member_2282" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2285" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations" xlink:label="Locator_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_2286" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2285" xlink:to="Locator_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_2286" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2257" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2258" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2257" xlink:to="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2258" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2261" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:label="Locator_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_2262" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2261" xlink:to="Locator_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_2262" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:label="Locator_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_2265" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="Locator_us-gaap_PlanAssetCategoriesDomain_2266" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_2265" xlink:to="Locator_us-gaap_PlanAssetCategoriesDomain_2266" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis" xlink:label="Locator_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_2287" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="Locator_us-gaap_PlanAssetCategoriesDomain_2288" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_2287" xlink:to="Locator_us-gaap_PlanAssetCategoriesDomain_2288" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="Locator_us-gaap_PlanAssetCategoriesDomain_2267" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquitySecuritiesMember" xlink:label="Locator_us-gaap_EquitySecuritiesMember_2268" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PlanAssetCategoriesDomain_2267" xlink:to="Locator_us-gaap_EquitySecuritiesMember_2268" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="Locator_us-gaap_PlanAssetCategoriesDomain_2269" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtSecuritiesMember" xlink:label="Locator_us-gaap_DebtSecuritiesMember_2270" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PlanAssetCategoriesDomain_2269" xlink:to="Locator_us-gaap_DebtSecuritiesMember_2270" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="Locator_us-gaap_PlanAssetCategoriesDomain_2271" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsMember" xlink:label="Locator_us-gaap_CashAndCashEquivalentsMember_2272" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PlanAssetCategoriesDomain_2271" xlink:to="Locator_us-gaap_CashAndCashEquivalentsMember_2272" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanAssetCategoriesDomain" xlink:label="Locator_us-gaap_PlanAssetCategoriesDomain_2273" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsMember" xlink:label="Locator_us-gaap_OtherAssetsMember_2274" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_PlanAssetCategoriesDomain_2273" xlink:to="Locator_us-gaap_OtherAssetsMember_2274" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2263" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2264" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2263" xlink:to="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2264" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2275" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2276" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2275" xlink:to="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2276" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2289" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2290" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2289" xlink:to="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2290" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2283" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:label="Locator_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_2284" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2283" xlink:to="Locator_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_2284" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/EmployeeBenefitPlansPlanAssetsDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2333" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="Locator_us-gaap_FairValueInputsLevel3Member_2334" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2333" xlink:to="Locator_us-gaap_FairValueInputsLevel3Member_2334" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2325" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2326" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2325" xlink:to="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2326" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2329" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2330" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_2329" xlink:to="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2330" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2331" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2332" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2331" xlink:to="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2332" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2335" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:label="Locator_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_2336" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2335" xlink:to="Locator_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_2336" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2337" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DefinedBenefitPlanPurchasesDuringYear" xlink:label="Locator_hbio_DefinedBenefitPlanPurchasesDuringYear_2338" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2337" xlink:to="Locator_hbio_DefinedBenefitPlanPurchasesDuringYear_2338" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2339" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DefinedBenefitPlanUnrealizedLossGain" xlink:label="Locator_hbio_DefinedBenefitPlanUnrealizedLossGain_2340" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2339" xlink:to="Locator_hbio_DefinedBenefitPlanUnrealizedLossGain_2340" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2341" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanSettlementsPlanAssets" xlink:label="Locator_us-gaap_DefinedBenefitPlanSettlementsPlanAssets_2342" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DefinedBenefitPlanDisclosureLineItems_2341" xlink:to="Locator_us-gaap_DefinedBenefitPlanSettlementsPlanAssets_2342" order="4.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/CapitalStockDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2365" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_2366" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2365" xlink:to="Locator_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_2366" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_2369" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2370" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_2369" xlink:to="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2370" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2371" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2372" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2371" xlink:to="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2372" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2441" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2442" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_2441" xlink:to="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2442" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2373" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsTwoCentsToTwoDollarsFortyTwoCentsMember" xlink:label="Locator_hbio_TwoDollarsTwoCentsToTwoDollarsFortyTwoCentsMember_2374" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2373" xlink:to="Locator_hbio_TwoDollarsTwoCentsToTwoDollarsFortyTwoCentsMember_2374" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2375" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsFortyThreeCentsToTwoDollarsSeventyTwoCentsMember" xlink:label="Locator_hbio_TwoDollarsFortyThreeCentsToTwoDollarsSeventyTwoCentsMember_2376" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2375" xlink:to="Locator_hbio_TwoDollarsFortyThreeCentsToTwoDollarsSeventyTwoCentsMember_2376" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2377" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsSeventyThreeCentstoThreeDollarsSixtyEightCentsMember" xlink:label="Locator_hbio_TwoDollarsSeventyThreeCentstoThreeDollarsSixtyEightCentsMember_2378" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2377" xlink:to="Locator_hbio_TwoDollarsSeventyThreeCentstoThreeDollarsSixtyEightCentsMember_2378" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2379" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ThreeDollarsSixtyNineCentsToFourDollarsSevenCentsMember" xlink:label="Locator_hbio_ThreeDollarsSixtyNineCentsToFourDollarsSevenCentsMember_2380" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2379" xlink:to="Locator_hbio_ThreeDollarsSixtyNineCentsToFourDollarsSevenCentsMember_2380" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2381" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsEightCentsToFourDollarsSeventeenCentsMember" xlink:label="Locator_hbio_FourDollarsEightCentsToFourDollarsSeventeenCentsMember_2382" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2381" xlink:to="Locator_hbio_FourDollarsEightCentsToFourDollarsSeventeenCentsMember_2382" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2383" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsEighteenCentsToFourDollarsTwentySixCentsMember" xlink:label="Locator_hbio_FourDollarsEighteenCentsToFourDollarsTwentySixCentsMember_2384" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2383" xlink:to="Locator_hbio_FourDollarsEighteenCentsToFourDollarsTwentySixCentsMember_2384" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2385" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsTwentySevenCentsToFourDollarsFortyOneCentsMember" xlink:label="Locator_hbio_FourDollarsTwentySevenCentsToFourDollarsFortyOneCentsMember_2386" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2385" xlink:to="Locator_hbio_FourDollarsTwentySevenCentsToFourDollarsFortyOneCentsMember_2386" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2387" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsFortyTwoCentsToFiveDollarsThirtyNineCentsMember" xlink:label="Locator_hbio_FourDollarsFortyTwoCentsToFiveDollarsThirtyNineCentsMember_2388" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2387" xlink:to="Locator_hbio_FourDollarsFortyTwoCentsToFiveDollarsThirtyNineCentsMember_2388" order="8.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2389" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FiveDollarsFortyCentsToFiveDollarsFiftyOneCentsMember" xlink:label="Locator_hbio_FiveDollarsFortyCentsToFiveDollarsFiftyOneCentsMember_2390" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2389" xlink:to="Locator_hbio_FiveDollarsFortyCentsToFiveDollarsFiftyOneCentsMember_2390" order="9.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2391" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FiveDollarsFiftyTwoCentsToFiveDollarsSixtyThreeCentsMember" xlink:label="Locator_hbio_FiveDollarsFiftyTwoCentsToFiveDollarsSixtyThreeCentsMember_2392" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2391" xlink:to="Locator_hbio_FiveDollarsFiftyTwoCentsToFiveDollarsSixtyThreeCentsMember_2392" order="10.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2393" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsTwoCentsToFiveDollarsSixtyThreeCentsMember" xlink:label="Locator_hbio_TwoDollarsTwoCentsToFiveDollarsSixtyThreeCentsMember_2394" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2393" xlink:to="Locator_hbio_TwoDollarsTwoCentsToFiveDollarsSixtyThreeCentsMember_2394" order="11.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2395" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_OneDollarFortyThreeCentsToTwoDollarsFifteenCentsMember" xlink:label="Locator_hbio_OneDollarFortyThreeCentsToTwoDollarsFifteenCentsMember_2396" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2395" xlink:to="Locator_hbio_OneDollarFortyThreeCentsToTwoDollarsFifteenCentsMember_2396" order="12.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2397" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsFourtyFiveCentsMember" xlink:label="Locator_hbio_TwoDollarsFourtyFiveCentsMember_2398" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2397" xlink:to="Locator_hbio_TwoDollarsFourtyFiveCentsMember_2398" order="13.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2399" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsFiftySixCentsMember" xlink:label="Locator_hbio_TwoDollarsFiftySixCentsMember_2400" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2399" xlink:to="Locator_hbio_TwoDollarsFiftySixCentsMember_2400" order="14.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2401" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsFiftyNineCentsToThreeDollarsFiftyFourCentsMember" xlink:label="Locator_hbio_TwoDollarsFiftyNineCentsToThreeDollarsFiftyFourCentsMember_2402" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2401" xlink:to="Locator_hbio_TwoDollarsFiftyNineCentsToThreeDollarsFiftyFourCentsMember_2402" order="15.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2403" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ThreeDollarsSixtyFourCentsMember" xlink:label="Locator_hbio_ThreeDollarsSixtyFourCentsMember_2404" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2403" xlink:to="Locator_hbio_ThreeDollarsSixtyFourCentsMember_2404" order="16.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2405" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ThreeDollarsSixtyEightCentsToThreeDollarsNinetyNineCentsMember" xlink:label="Locator_hbio_ThreeDollarsSixtyEightCentsToThreeDollarsNinetyNineCentsMember_2406" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2405" xlink:to="Locator_hbio_ThreeDollarsSixtyEightCentsToThreeDollarsNinetyNineCentsMember_2406" order="17.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2407" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsFourCentsMember" xlink:label="Locator_hbio_FourDollarsFourCentsMember_2408" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2407" xlink:to="Locator_hbio_FourDollarsFourCentsMember_2408" order="18.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2409" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsTwentyOneCentsToFourDollarsThirtyOneCentsMember" xlink:label="Locator_hbio_FourDollarsTwentyOneCentsToFourDollarsThirtyOneCentsMember_2410" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2409" xlink:to="Locator_hbio_FourDollarsTwentyOneCentsToFourDollarsThirtyOneCentsMember_2410" order="19.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2411" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FiveDollarsSeventyThreeCentsToSixDollarsFiftySevenCentsMember" xlink:label="Locator_hbio_FiveDollarsSeventyThreeCentsToSixDollarsFiftySevenCentsMember_2412" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2411" xlink:to="Locator_hbio_FiveDollarsSeventyThreeCentsToSixDollarsFiftySevenCentsMember_2412" order="20.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2413" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsSevenCentsToFourDollarsTenCentsMemberMember" xlink:label="Locator_hbio_FourDollarsSevenCentsToFourDollarsTenCentsMemberMember_2414" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2413" xlink:to="Locator_hbio_FourDollarsSevenCentsToFourDollarsTenCentsMemberMember_2414" order="21.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2415" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_FourDollarsTwelveCentsToFourDollarsEightyNineCentsMember" xlink:label="Locator_hbio_FourDollarsTwelveCentsToFourDollarsEightyNineCentsMember_2416" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2415" xlink:to="Locator_hbio_FourDollarsTwelveCentsToFourDollarsEightyNineCentsMember_2416" order="22.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2417" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_OneDollarFortyThreeCentsToSixDollarsFiftySevenCentsMember" xlink:label="Locator_hbio_OneDollarFortyThreeCentsToSixDollarsFiftySevenCentsMember_2418" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2417" xlink:to="Locator_hbio_OneDollarFortyThreeCentsToSixDollarsFiftySevenCentsMember_2418" order="23.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2419" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_OneDollarRortyThreeCentsToFourDollarsEightyNineCentsMember" xlink:label="Locator_hbio_OneDollarRortyThreeCentsToFourDollarsEightyNineCentsMember_2420" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2419" xlink:to="Locator_hbio_OneDollarRortyThreeCentsToFourDollarsEightyNineCentsMember_2420" order="24.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2421" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsFortyThreeCentsToTwoDollarsFiftyEightCentsMember" xlink:label="Locator_hbio_TwoDollarsFortyThreeCentsToTwoDollarsFiftyEightCentsMember_2422" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2421" xlink:to="Locator_hbio_TwoDollarsFortyThreeCentsToTwoDollarsFiftyEightCentsMember_2422" order="25.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2423" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TwoDollarsFiftyNineCentsToThreeDollarsFiftyNineCentsMember" xlink:label="Locator_hbio_TwoDollarsFiftyNineCentsToThreeDollarsFiftyNineCentsMember_2424" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2423" xlink:to="Locator_hbio_TwoDollarsFiftyNineCentsToThreeDollarsFiftyNineCentsMember_2424" order="26.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2425" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ThreeDollarsSixtyCentsToThreeDollarsSixtyEightCentsMember" xlink:label="Locator_hbio_ThreeDollarsSixtyCentsToThreeDollarsSixtyEightCentsMember_2426" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_2425" xlink:to="Locator_hbio_ThreeDollarsSixtyCentsToThreeDollarsSixtyEightCentsMember_2426" order="27.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2427" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_2428" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2427" xlink:to="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_2428" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2429" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_2430" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2429" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_2430" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2431" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_2432" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2431" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_2432" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2433" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_2434" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2433" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_2434" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2435" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_2436" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2435" xlink:to="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_2436" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2437" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_2438" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2437" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_2438" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2439" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_2440" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2439" xlink:to="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_2440" order="7.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/RevenuesDeferredRevenueDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementLineItems" xlink:label="Locator_us-gaap_DeferredRevenueArrangementLineItems_2529" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MovementInDeferredRevenueRollForward" xlink:label="Locator_us-gaap_MovementInDeferredRevenueRollForward_2530" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DeferredRevenueArrangementLineItems_2529" xlink:to="Locator_us-gaap_MovementInDeferredRevenueRollForward_2530" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MovementInDeferredRevenueRollForward" xlink:label="Locator_us-gaap_MovementInDeferredRevenueRollForward_2531" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenue" xlink:label="Locator_us-gaap_DeferredRevenue_2532" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_MovementInDeferredRevenueRollForward_2531" xlink:to="Locator_us-gaap_DeferredRevenue_2532" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MovementInDeferredRevenueRollForward" xlink:label="Locator_us-gaap_MovementInDeferredRevenueRollForward_2533" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DeferredRevenueAdditionsDueToBusinessCombination" xlink:label="Locator_hbio_DeferredRevenueAdditionsDueToBusinessCombination_2534" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_MovementInDeferredRevenueRollForward_2533" xlink:to="Locator_hbio_DeferredRevenueAdditionsDueToBusinessCombination_2534" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MovementInDeferredRevenueRollForward" xlink:label="Locator_us-gaap_MovementInDeferredRevenueRollForward_2535" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueAdditions" xlink:label="Locator_us-gaap_DeferredRevenueAdditions_2536" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_MovementInDeferredRevenueRollForward_2535" xlink:to="Locator_us-gaap_DeferredRevenueAdditions_2536" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MovementInDeferredRevenueRollForward" xlink:label="Locator_us-gaap_MovementInDeferredRevenueRollForward_2537" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueRevenueRecognized1" xlink:label="Locator_us-gaap_DeferredRevenueRevenueRecognized1_2538" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_MovementInDeferredRevenueRollForward_2537" xlink:to="Locator_us-gaap_DeferredRevenueRevenueRecognized1_2538" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MovementInDeferredRevenueRollForward" xlink:label="Locator_us-gaap_MovementInDeferredRevenueRollForward_2539" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealized" xlink:label="Locator_us-gaap_ForeignCurrencyTransactionGainLossRealized_2540" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_MovementInDeferredRevenueRollForward_2539" xlink:to="Locator_us-gaap_ForeignCurrencyTransactionGainLossRealized_2540" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementLineItems" xlink:label="Locator_us-gaap_DeferredRevenueArrangementLineItems_2519" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementByTypeTable" xlink:label="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_2520" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DeferredRevenueArrangementLineItems_2519" xlink:to="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_2520" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementByTypeTable" xlink:label="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_2521" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_2522" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_2521" xlink:to="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_2522" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_2523" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2524" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_2523" xlink:to="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2524" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_2541" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2542" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_2541" xlink:to="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2542" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2525" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ServiceContractsMember" xlink:label="Locator_hbio_ServiceContractsMember_2526" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2525" xlink:to="Locator_hbio_ServiceContractsMember_2526" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2527" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CustomerAdvancesMember" xlink:label="Locator_hbio_CustomerAdvancesMember_2528" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_2527" xlink:to="Locator_hbio_CustomerAdvancesMember_2528" order="2.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsLineItems" xlink:label="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsLineItems_2569" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfQuantifyingPriorYearMisstatementCorrectedInCurrentYearFinancialStatementsTable" xlink:label="Locator_us-gaap_ScheduleOfQuantifyingPriorYearMisstatementCorrectedInCurrentYearFinancialStatementsTable_2570" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsLineItems_2569" xlink:to="Locator_us-gaap_ScheduleOfQuantifyingPriorYearMisstatementCorrectedInCurrentYearFinancialStatementsTable_2570" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfQuantifyingPriorYearMisstatementCorrectedInCurrentYearFinancialStatementsTable" xlink:label="Locator_us-gaap_ScheduleOfQuantifyingPriorYearMisstatementCorrectedInCurrentYearFinancialStatementsTable_2571" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis" xlink:label="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis_2572" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfQuantifyingPriorYearMisstatementCorrectedInCurrentYearFinancialStatementsTable_2571" xlink:to="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis_2572" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis" xlink:label="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis_2573" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NatureOfErrorDomain" xlink:label="Locator_us-gaap_NatureOfErrorDomain_2574" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis_2573" xlink:to="Locator_us-gaap_NatureOfErrorDomain_2574" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis" xlink:label="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis_2579" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NatureOfErrorDomain" xlink:label="Locator_us-gaap_NatureOfErrorDomain_2580" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsByNatureOfErrorAxis_2579" xlink:to="Locator_us-gaap_NatureOfErrorDomain_2580" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NatureOfErrorDomain" xlink:label="Locator_us-gaap_NatureOfErrorDomain_2575" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ClassificationOfTheCompanysExcessCashFlowPaymentMember" xlink:label="Locator_hbio_ClassificationOfTheCompanysExcessCashFlowPaymentMember_2576" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_NatureOfErrorDomain_2575" xlink:to="Locator_hbio_ClassificationOfTheCompanysExcessCashFlowPaymentMember_2576" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsLineItems" xlink:label="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsLineItems_2577" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsAmount" xlink:label="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsAmount_2578" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsLineItems_2577" xlink:to="Locator_us-gaap_QuantifyingMisstatementInCurrentYearFinancialStatementsAmount_2578" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/DerivativeNarrativesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2639" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="Locator_us-gaap_InterestRateSwapMember_2640" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2639" xlink:to="Locator_us-gaap_InterestRateSwapMember_2640" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2619" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2620" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2619" xlink:to="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2620" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2623" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="Locator_us-gaap_DerivativeInstrumentRiskAxis_2624" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2623" xlink:to="Locator_us-gaap_DerivativeInstrumentRiskAxis_2624" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="Locator_us-gaap_DerivativeInstrumentRiskAxis_2629" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="Locator_us-gaap_DerivativeContractTypeDomain_2630" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_DerivativeInstrumentRiskAxis_2629" xlink:to="Locator_us-gaap_DerivativeContractTypeDomain_2630" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="Locator_us-gaap_DerivativeInstrumentRiskAxis_2663" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="Locator_us-gaap_DerivativeContractTypeDomain_2664" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_DerivativeInstrumentRiskAxis_2663" xlink:to="Locator_us-gaap_DerivativeContractTypeDomain_2664" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="Locator_us-gaap_DerivativeContractTypeDomain_2631" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DelayedDrawdownTermLoanMember" xlink:label="Locator_hbio_DelayedDrawdownTermLoanMember_2632" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeContractTypeDomain_2631" xlink:to="Locator_hbio_DelayedDrawdownTermLoanMember_2632" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="Locator_us-gaap_DerivativeContractTypeDomain_2633" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="Locator_us-gaap_SecuredDebtMember_2634" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeContractTypeDomain_2633" xlink:to="Locator_us-gaap_SecuredDebtMember_2634" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2625" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="Locator_us-gaap_BalanceSheetLocationAxis_2626" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2625" xlink:to="Locator_us-gaap_BalanceSheetLocationAxis_2626" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="Locator_us-gaap_BalanceSheetLocationAxis_2635" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="Locator_us-gaap_BalanceSheetLocationDomain_2636" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_BalanceSheetLocationAxis_2635" xlink:to="Locator_us-gaap_BalanceSheetLocationDomain_2636" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="Locator_us-gaap_BalanceSheetLocationDomain_2637" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLiabilitiesMember" xlink:label="Locator_us-gaap_OtherLiabilitiesMember_2638" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BalanceSheetLocationDomain_2637" xlink:to="Locator_us-gaap_OtherLiabilitiesMember_2638" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2627" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2628" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_2627" xlink:to="Locator_us-gaap_FinancialInstrumentAxis_2628" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2641" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2642" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FinancialInstrumentAxis_2641" xlink:to="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2642" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2665" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2666" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_FinancialInstrumentAxis_2665" xlink:to="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2666" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2643" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MinimunPercentageOfTermLoanAndDelayedDrawTermLoanOnWhichInterestRateRequiredToBeFixed" xlink:label="Locator_hbio_MinimunPercentageOfTermLoanAndDelayedDrawTermLoanOnWhichInterestRateRequiredToBeFixed_2644" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2643" xlink:to="Locator_hbio_MinimunPercentageOfTermLoanAndDelayedDrawTermLoanOnWhichInterestRateRequiredToBeFixed_2644" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2645" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeAssetNotionalAmount" xlink:label="Locator_us-gaap_DerivativeAssetNotionalAmount_2646" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2645" xlink:to="Locator_us-gaap_DerivativeAssetNotionalAmount_2646" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2647" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_LiborFixedRate" xlink:label="Locator_hbio_LiborFixedRate_2648" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2647" xlink:to="Locator_hbio_LiborFixedRate_2648" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2649" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_2650" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2649" xlink:to="Locator_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_2650" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2651" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="Locator_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2652" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2651" xlink:to="Locator_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2652" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2653" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DerivativeInterestRateSwapEffectivePercentage" xlink:label="Locator_hbio_DerivativeInterestRateSwapEffectivePercentage_2654" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2653" xlink:to="Locator_hbio_DerivativeInterestRateSwapEffectivePercentage_2654" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2655" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebt" xlink:label="Locator_us-gaap_SecuredDebt_2656" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2655" xlink:to="Locator_us-gaap_SecuredDebt_2656" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2657" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="Locator_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_2658" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2657" xlink:to="Locator_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_2658" order="8.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2659" />
        <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="Locator_invest_DerivativeNotionalAmount_2660" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2659" xlink:to="Locator_invest_DerivativeNotionalAmount_2660" order="9.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2661" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromDerivativeInstrumentFinancingActivities" xlink:label="Locator_us-gaap_ProceedsFromDerivativeInstrumentFinancingActivities_2662" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_2661" xlink:to="Locator_us-gaap_ProceedsFromDerivativeInstrumentFinancingActivities_2662" order="10.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/DerivativeDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2701" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="Locator_us-gaap_InterestRateSwapMember_2702" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2701" xlink:to="Locator_us-gaap_InterestRateSwapMember_2702" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="Locator_us-gaap_BalanceSheetLocationAxis_2703" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="Locator_us-gaap_BalanceSheetLocationDomain_2704" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_BalanceSheetLocationAxis_2703" xlink:to="Locator_us-gaap_BalanceSheetLocationDomain_2704" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="Locator_us-gaap_BalanceSheetLocationAxis_2713" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="Locator_us-gaap_BalanceSheetLocationDomain_2714" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_BalanceSheetLocationAxis_2713" xlink:to="Locator_us-gaap_BalanceSheetLocationDomain_2714" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="Locator_us-gaap_BalanceSheetLocationDomain_2705" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLiabilitiesMember" xlink:label="Locator_us-gaap_OtherLiabilitiesMember_2706" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BalanceSheetLocationDomain_2705" xlink:to="Locator_us-gaap_OtherLiabilitiesMember_2706" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2707" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2708" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FinancialInstrumentAxis_2707" xlink:to="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2708" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativesFairValueLineItems" xlink:label="Locator_us-gaap_DerivativesFairValueLineItems_2693" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:label="Locator_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_2694" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DerivativesFairValueLineItems_2693" xlink:to="Locator_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_2694" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:label="Locator_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_2697" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="Locator_us-gaap_BalanceSheetLocationAxis_2698" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_2697" xlink:to="Locator_us-gaap_BalanceSheetLocationAxis_2698" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:label="Locator_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_2699" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2700" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_2699" xlink:to="Locator_us-gaap_FinancialInstrumentAxis_2700" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativesFairValueLineItems" xlink:label="Locator_us-gaap_DerivativesFairValueLineItems_2709" />
        <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="Locator_invest_DerivativeNotionalAmount_2710" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativesFairValueLineItems_2709" xlink:to="Locator_invest_DerivativeNotionalAmount_2710" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativesFairValueLineItems" xlink:label="Locator_us-gaap_DerivativesFairValueLineItems_2711" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" xlink:label="Locator_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_2712" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativesFairValueLineItems_2711" xlink:to="Locator_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_2712" order="2.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/DerivativeOtherComprehensiveIncomeLossDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2741" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="Locator_us-gaap_InterestRateSwapMember_2742" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2741" xlink:to="Locator_us-gaap_InterestRateSwapMember_2742" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2747" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2748" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FinancialInstrumentAxis_2747" xlink:to="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2748" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossLineItems_2733" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_2734" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DerivativeInstrumentsGainLossLineItems_2733" xlink:to="Locator_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_2734" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_2737" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2738" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_2737" xlink:to="Locator_us-gaap_FinancialInstrumentAxis_2738" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_2739" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="Locator_us-gaap_IncomeStatementLocationAxis_2740" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_2739" xlink:to="Locator_us-gaap_IncomeStatementLocationAxis_2740" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="Locator_us-gaap_IncomeStatementLocationAxis_2743" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_2744" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_IncomeStatementLocationAxis_2743" xlink:to="Locator_us-gaap_IncomeStatementLocationDomain_2744" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="Locator_us-gaap_IncomeStatementLocationDomain_2745" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpenseMember" xlink:label="Locator_us-gaap_InterestExpenseMember_2746" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_IncomeStatementLocationDomain_2745" xlink:to="Locator_us-gaap_InterestExpenseMember_2746" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossLineItems_2749" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax" xlink:label="Locator_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax_2750" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsGainLossLineItems_2749" xlink:to="Locator_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax_2750" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossLineItems_2751" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet" xlink:label="Locator_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_2752" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DerivativeInstrumentsGainLossLineItems_2751" xlink:to="Locator_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_2752" order="2.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/FairValueMeasurementsDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2785" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="Locator_us-gaap_FairValueInputsLevel1Member_2786" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2785" xlink:to="Locator_us-gaap_FairValueInputsLevel1Member_2786" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2787" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="Locator_us-gaap_FairValueInputsLevel2Member_2788" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2787" xlink:to="Locator_us-gaap_FairValueInputsLevel2Member_2788" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2789" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="Locator_us-gaap_FairValueInputsLevel3Member_2790" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2789" xlink:to="Locator_us-gaap_FairValueInputsLevel3Member_2790" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2791" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="Locator_us-gaap_InterestRateSwapMember_2792" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2791" xlink:to="Locator_us-gaap_InterestRateSwapMember_2792" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2783" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2784" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2783" xlink:to="Locator_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2784" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2793" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2794" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_FinancialInstrumentAxis_2793" xlink:to="Locator_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2794" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2775" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2776" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2775" xlink:to="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2776" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2779" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2780" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2779" xlink:to="Locator_us-gaap_FairValueByFairValueHierarchyLevelAxis_2780" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2781" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="Locator_us-gaap_FinancialInstrumentAxis_2782" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2781" xlink:to="Locator_us-gaap_FinancialInstrumentAxis_2782" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2795" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:label="Locator_us-gaap_DerivativeLiabilities_2796" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2795" xlink:to="Locator_us-gaap_DerivativeLiabilities_2796" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/AccumulatedOtherComprehensiveIncomeDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2831" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_2832" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2831" xlink:to="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_2832" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_2839" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="Locator_us-gaap_StatementEquityComponentsAxis_2840" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_2839" xlink:to="Locator_us-gaap_StatementEquityComponentsAxis_2840" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="Locator_us-gaap_StatementEquityComponentsAxis_2841" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_2842" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_StatementEquityComponentsAxis_2841" xlink:to="Locator_us-gaap_EquityComponentDomain_2842" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="Locator_us-gaap_StatementEquityComponentsAxis_2857" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_2858" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_StatementEquityComponentsAxis_2857" xlink:to="Locator_us-gaap_EquityComponentDomain_2858" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_2843" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="Locator_us-gaap_AccumulatedTranslationAdjustmentMember_2844" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_2843" xlink:to="Locator_us-gaap_AccumulatedTranslationAdjustmentMember_2844" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_2845" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember" xlink:label="Locator_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_2846" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_2845" xlink:to="Locator_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_2846" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_2847" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" xlink:label="Locator_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_2848" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_2847" xlink:to="Locator_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_2848" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2849" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_2850" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2849" xlink:to="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_2850" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2851" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" xlink:label="Locator_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_2852" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2851" xlink:to="Locator_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_2852" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2853" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="Locator_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_2854" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2853" xlink:to="Locator_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_2854" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2855" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="Locator_us-gaap_OtherComprehensiveIncomeLossNetOfTax_2856" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_2855" xlink:to="Locator_us-gaap_OtherComprehensiveIncomeLossNetOfTax_2856" order="4.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/LongTermDebtBorrowingsDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="Locator_us-gaap_LongTermDebtNoncurrent_2923" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnamortizedDebtIssuanceExpense" xlink:label="Locator_us-gaap_UnamortizedDebtIssuanceExpense_2924" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_LongTermDebtNoncurrent_2923" xlink:to="Locator_us-gaap_UnamortizedDebtIssuanceExpense_2924" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2887" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="Locator_us-gaap_DebtInstrumentTable_2888" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2887" xlink:to="Locator_us-gaap_DebtInstrumentTable_2888" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="Locator_us-gaap_DebtInstrumentTable_2901" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="Locator_us-gaap_LongtermDebtTypeAxis_2902" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DebtInstrumentTable_2901" xlink:to="Locator_us-gaap_LongtermDebtTypeAxis_2902" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="Locator_us-gaap_LongtermDebtTypeAxis_2905" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_2906" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_LongtermDebtTypeAxis_2905" xlink:to="Locator_us-gaap_LongtermDebtTypeDomain_2906" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="Locator_us-gaap_LongtermDebtTypeDomain_2903" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DeferredFinancingCostsMember" xlink:label="Locator_hbio_DeferredFinancingCostsMember_2904" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_LongtermDebtTypeDomain_2903" xlink:to="Locator_hbio_DeferredFinancingCostsMember_2904" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2907" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermLoansPayable" xlink:label="Locator_us-gaap_LongTermLoansPayable_2908" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2907" xlink:to="Locator_us-gaap_LongTermLoansPayable_2908" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2909" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DelayedDrawdownTermLoan" xlink:label="Locator_hbio_DelayedDrawdownTermLoan_2910" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2909" xlink:to="Locator_hbio_DelayedDrawdownTermLoan_2910" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2911" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_RevolvingCreditFacility" xlink:label="Locator_hbio_RevolvingCreditFacility_2912" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2911" xlink:to="Locator_hbio_RevolvingCreditFacility_2912" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2913" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="Locator_us-gaap_DeferredFinanceCostsNet_2914" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2913" xlink:to="Locator_us-gaap_DeferredFinanceCostsNet_2914" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2915" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SecuredDebt" xlink:label="Locator_us-gaap_SecuredDebt_2916" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2915" xlink:to="Locator_us-gaap_SecuredDebt_2916" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2917" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LoansPayableCurrent" xlink:label="Locator_us-gaap_LoansPayableCurrent_2918" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2917" xlink:to="Locator_us-gaap_LoansPayableCurrent_2918" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2919" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsCurrentNet" xlink:label="Locator_us-gaap_DeferredFinanceCostsCurrentNet_2920" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2919" xlink:to="Locator_us-gaap_DeferredFinanceCostsCurrentNet_2920" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="Locator_us-gaap_DebtInstrumentLineItems_2921" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="Locator_us-gaap_LongTermDebtNoncurrent_2922" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DebtInstrumentLineItems_2921" xlink:to="Locator_us-gaap_LongTermDebtNoncurrent_2922" order="8.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/RelatedPartyTransactionsNarrativesDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="Locator_us-gaap_RelatedPartyTransactionDomain_2959" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_McsGmbhMcsAndTriangleBiosystemsIncMember" xlink:label="Locator_hbio_McsGmbhMcsAndTriangleBiosystemsIncMember_2960" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_RelatedPartyTransactionDomain_2959" xlink:to="Locator_hbio_McsGmbhMcsAndTriangleBiosystemsIncMember_2960" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_2941" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2942" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_2941" xlink:to="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2942" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2945" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="Locator_us-gaap_BusinessAcquisitionAxis_2946" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2945" xlink:to="Locator_us-gaap_BusinessAcquisitionAxis_2946" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="Locator_us-gaap_BusinessAcquisitionAxis_2949" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2950" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_BusinessAcquisitionAxis_2949" xlink:to="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2950" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="Locator_us-gaap_BusinessAcquisitionAxis_2969" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2970" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_BusinessAcquisitionAxis_2969" xlink:to="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2970" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2951" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MultiChannelSystemsMcsGmbhMember" xlink:label="Locator_hbio_MultiChannelSystemsMcsGmbhMember_2952" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2951" xlink:to="Locator_hbio_MultiChannelSystemsMcsGmbhMember_2952" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2953" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TriangleBiosystemsIncMember" xlink:label="Locator_hbio_TriangleBiosystemsIncMember_2954" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2953" xlink:to="Locator_hbio_TriangleBiosystemsIncMember_2954" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2955" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_HekaElektronikMember" xlink:label="Locator_hbio_HekaElektronikMember_2956" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionAcquireeDomain_2955" xlink:to="Locator_hbio_HekaElektronikMember_2956" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2947" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:label="Locator_us-gaap_RelatedPartyTransactionAxis_2948" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_2947" xlink:to="Locator_us-gaap_RelatedPartyTransactionAxis_2948" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:label="Locator_us-gaap_RelatedPartyTransactionAxis_2957" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="Locator_us-gaap_RelatedPartyTransactionDomain_2958" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_RelatedPartyTransactionAxis_2957" xlink:to="Locator_us-gaap_RelatedPartyTransactionDomain_2958" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:label="Locator_us-gaap_RelatedPartyTransactionAxis_2971" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="Locator_us-gaap_RelatedPartyTransactionDomain_2972" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_RelatedPartyTransactionAxis_2971" xlink:to="Locator_us-gaap_RelatedPartyTransactionDomain_2972" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_2961" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet" xlink:label="Locator_us-gaap_OperatingLeasesRentExpenseNet_2962" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_2961" xlink:to="Locator_us-gaap_OperatingLeasesRentExpenseNet_2962" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_2963" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesRentExpenseSubleaseRentals1" xlink:label="Locator_us-gaap_OperatingLeasesRentExpenseSubleaseRentals1_2964" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_2963" xlink:to="Locator_us-gaap_OperatingLeasesRentExpenseSubleaseRentals1_2964" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_2965" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_TransitionServicesChargedToSpinnee" xlink:label="Locator_hbio_TransitionServicesChargedToSpinnee_2966" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_2965" xlink:to="Locator_hbio_TransitionServicesChargedToSpinnee_2966" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="Locator_us-gaap_BusinessAcquisitionLineItems_2967" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_DistributionRevenuesFromSpinnee" xlink:label="Locator_hbio_DistributionRevenuesFromSpinnee_2968" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_BusinessAcquisitionLineItems_2967" xlink:to="Locator_hbio_DistributionRevenuesFromSpinnee_2968" order="4.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/RevenuesTables">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementLineItems" xlink:label="Locator_us-gaap_DeferredRevenueArrangementLineItems_3153" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementByTypeTable" xlink:label="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_3154" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DeferredRevenueArrangementLineItems_3153" xlink:to="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_3154" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementByTypeTable" xlink:label="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_3155" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_3156" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DeferredRevenueArrangementByTypeTable_3155" xlink:to="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_3156" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_3157" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_3158" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_DeferredRevenueArrangementTypeAxis_3157" xlink:to="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_3158" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_3159" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ServiceContractsMember" xlink:label="Locator_hbio_ServiceContractsMember_3160" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_3159" xlink:to="Locator_hbio_ServiceContractsMember_3160" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_3161" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_CustomerAdvancesMember" xlink:label="Locator_hbio_CustomerAdvancesMember_3162" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DeferredRevenueArrangementTypeDomain_3161" xlink:to="Locator_hbio_CustomerAdvancesMember_3162" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueArrangementLineItems" xlink:label="Locator_us-gaap_DeferredRevenueArrangementLineItems_3163" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRevenueByArrangementDisclosureTextBlock" xlink:label="Locator_us-gaap_DeferredRevenueByArrangementDisclosureTextBlock_3164" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DeferredRevenueArrangementLineItems_3163" xlink:to="Locator_us-gaap_DeferredRevenueByArrangementDisclosureTextBlock_3164" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/RevenuesDisaggregationDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="Locator_srt_ProductsAndServicesDomain_3197" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_InstrumentsEquipmentAndAccessoriesMember" xlink:label="Locator_hbio_InstrumentsEquipmentAndAccessoriesMember_3198" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_ProductsAndServicesDomain_3197" xlink:to="Locator_hbio_InstrumentsEquipmentAndAccessoriesMember_3198" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="Locator_srt_ProductsAndServicesDomain_3199" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ServiceMaintenanceAndWarrantyContractsMember" xlink:label="Locator_hbio_ServiceMaintenanceAndWarrantyContractsMember_3200" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_ProductsAndServicesDomain_3199" xlink:to="Locator_hbio_ServiceMaintenanceAndWarrantyContractsMember_3200" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="Locator_srt_SegmentGeographicalDomain_3187" />
        <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="Locator_country_US_3188" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_SegmentGeographicalDomain_3187" xlink:to="Locator_country_US_3188" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="Locator_srt_SegmentGeographicalDomain_3189" />
        <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_GB" xlink:label="Locator_country_GB_3190" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_SegmentGeographicalDomain_3189" xlink:to="Locator_country_GB_3190" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="Locator_srt_SegmentGeographicalDomain_3191" />
        <loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_DE" xlink:label="Locator_country_DE_3192" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_SegmentGeographicalDomain_3191" xlink:to="Locator_country_DE_3192" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="Locator_srt_SegmentGeographicalDomain_3193" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_RestOfWorldMember" xlink:label="Locator_hbio_RestOfWorldMember_3194" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_srt_SegmentGeographicalDomain_3193" xlink:to="Locator_hbio_RestOfWorldMember_3194" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="Locator_us-gaap_DisaggregationOfRevenueLineItems_3179" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="Locator_us-gaap_DisaggregationOfRevenueTable_3180" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_DisaggregationOfRevenueLineItems_3179" xlink:to="Locator_us-gaap_DisaggregationOfRevenueTable_3180" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="Locator_us-gaap_DisaggregationOfRevenueTable_3181" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="Locator_srt_StatementGeographicalAxis_3182" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DisaggregationOfRevenueTable_3181" xlink:to="Locator_srt_StatementGeographicalAxis_3182" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="Locator_srt_StatementGeographicalAxis_3185" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="Locator_srt_SegmentGeographicalDomain_3186" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_srt_StatementGeographicalAxis_3185" xlink:to="Locator_srt_SegmentGeographicalDomain_3186" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="Locator_srt_StatementGeographicalAxis_3203" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="Locator_srt_SegmentGeographicalDomain_3204" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_srt_StatementGeographicalAxis_3203" xlink:to="Locator_srt_SegmentGeographicalDomain_3204" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="Locator_us-gaap_DisaggregationOfRevenueTable_3183" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="Locator_srt_ProductOrServiceAxis_3184" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_DisaggregationOfRevenueTable_3183" xlink:to="Locator_srt_ProductOrServiceAxis_3184" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="Locator_srt_ProductOrServiceAxis_3195" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="Locator_srt_ProductsAndServicesDomain_3196" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_srt_ProductOrServiceAxis_3195" xlink:to="Locator_srt_ProductsAndServicesDomain_3196" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="Locator_srt_ProductOrServiceAxis_3205" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="Locator_srt_ProductsAndServicesDomain_3206" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_srt_ProductOrServiceAxis_3205" xlink:to="Locator_srt_ProductsAndServicesDomain_3206" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="Locator_us-gaap_DisaggregationOfRevenueLineItems_3201" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Revenues" xlink:label="Locator_us-gaap_Revenues_3202" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_DisaggregationOfRevenueLineItems_3201" xlink:to="Locator_us-gaap_Revenues_3202" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/RecentlyIssuedAccountingPronouncementsDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_3235" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_3236" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_3235" xlink:to="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_3236" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_3241" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_3242" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_3241" xlink:to="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_3242" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_3243" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_3244" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_3243" xlink:to="Locator_us-gaap_TypeOfAdoptionMember_3244" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_3255" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_3256" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="Locator_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_3255" xlink:to="Locator_us-gaap_TypeOfAdoptionMember_3256" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_3245" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="Locator_us-gaap_AccountingStandardsUpdate201602Member_3246" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TypeOfAdoptionMember_3245" xlink:to="Locator_us-gaap_AccountingStandardsUpdate201602Member_3246" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_3247" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201712Member" xlink:label="Locator_us-gaap_AccountingStandardsUpdate201712Member_3248" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TypeOfAdoptionMember_3247" xlink:to="Locator_us-gaap_AccountingStandardsUpdate201712Member_3248" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_3249" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:label="Locator_us-gaap_AccountingStandardsUpdate201409Member_3250" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TypeOfAdoptionMember_3249" xlink:to="Locator_us-gaap_AccountingStandardsUpdate201409Member_3250" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="Locator_us-gaap_TypeOfAdoptionMember_3251" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201709Member" xlink:label="Locator_us-gaap_AccountingStandardsUpdate201709Member_3252" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_TypeOfAdoptionMember_3251" xlink:to="Locator_us-gaap_AccountingStandardsUpdate201709Member_3252" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_3253" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleDescription" xlink:label="Locator_us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleDescription_3254" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_3253" xlink:to="Locator_us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleDescription_3254" order="1.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/CapitalStockAssumptionsBlackScholesAndMonteCarloDetails">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="Locator_us-gaap_ValuationTechniqueDomain_3291" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_BlackScholesOptionPricingModelMember" xlink:label="Locator_hbio_BlackScholesOptionPricingModelMember_3292" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ValuationTechniqueDomain_3291" xlink:to="Locator_hbio_BlackScholesOptionPricingModelMember_3292" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="Locator_us-gaap_ValuationTechniqueDomain_3293" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_MonteCarloValuationSimulationMember" xlink:label="Locator_hbio_MonteCarloValuationSimulationMember_3294" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ValuationTechniqueDomain_3293" xlink:to="Locator_hbio_MonteCarloValuationSimulationMember_3294" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3275" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3276" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3275" xlink:to="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3276" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3287" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="Locator_us-gaap_ValuationTechniqueAxis_3288" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_3287" xlink:to="Locator_us-gaap_ValuationTechniqueAxis_3288" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueAxis" xlink:label="Locator_us-gaap_ValuationTechniqueAxis_3289" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ValuationTechniqueDomain" xlink:label="Locator_us-gaap_ValuationTechniqueDomain_3290" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_ValuationTechniqueAxis_3289" xlink:to="Locator_us-gaap_ValuationTechniqueDomain_3290" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3295" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3296" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3295" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3296" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3297" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_3298" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3297" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_3298" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3299" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_3300" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3299" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_3300" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3301" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_3302" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3301" xlink:to="Locator_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_3302" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3303" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCorrelationCoefficient" xlink:label="Locator_hbio_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCorrelationCoefficient_3304" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3303" xlink:to="Locator_hbio_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCorrelationCoefficient_3304" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3305" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_3306" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_3305" xlink:to="Locator_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_3306" order="5.0" />
    </definitionLink>
    <definitionLink xlink:type="extended" xlink:role="http://www.harvardbioscience.com/role/CONSOLIDATEDSTATEMENTOFSTOCKHOLDERSEQUITY">
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="Locator_us-gaap_StatementEquityComponentsAxis_3361" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_3362" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="Locator_us-gaap_StatementEquityComponentsAxis_3361" xlink:to="Locator_us-gaap_EquityComponentDomain_3362" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_3363" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="Locator_us-gaap_CommonStockMember_3364" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_3363" xlink:to="Locator_us-gaap_CommonStockMember_3364" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_3365" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="Locator_us-gaap_AdditionalPaidInCapitalMember_3366" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_3365" xlink:to="Locator_us-gaap_AdditionalPaidInCapitalMember_3366" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_3367" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="Locator_us-gaap_RetainedEarningsMember_3368" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_3367" xlink:to="Locator_us-gaap_RetainedEarningsMember_3368" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_3369" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeMember_3370" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_3369" xlink:to="Locator_us-gaap_AccumulatedOtherComprehensiveIncomeMember_3370" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="Locator_us-gaap_EquityComponentDomain_3371" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="Locator_us-gaap_TreasuryStockMember_3372" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_EquityComponentDomain_3371" xlink:to="Locator_us-gaap_TreasuryStockMember_3372" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3357" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="Locator_us-gaap_StatementTable_3358" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="Locator_us-gaap_StatementLineItems_3357" xlink:to="Locator_us-gaap_StatementTable_3358" order="-1.0" xbrldt:contextElement="segment" xbrldt:closed="true" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="Locator_us-gaap_StatementTable_3359" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="Locator_us-gaap_StatementEquityComponentsAxis_3360" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="Locator_us-gaap_StatementTable_3359" xlink:to="Locator_us-gaap_StatementEquityComponentsAxis_3360" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3373" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="Locator_us-gaap_StockholdersEquity_3374" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3373" xlink:to="Locator_us-gaap_StockholdersEquity_3374" order="1.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3375" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_3376" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3375" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_3376" order="2.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3377" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_3378" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3377" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_3378" order="3.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3379" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_3380" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3379" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_3380" order="4.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3381" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_SharesWithheldForTaxesValue" xlink:label="Locator_hbio_SharesWithheldForTaxesValue_3382" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3381" xlink:to="Locator_hbio_SharesWithheldForTaxesValue_3382" order="5.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3383" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockOptionPlanExpense" xlink:label="Locator_us-gaap_StockOptionPlanExpense_3384" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3383" xlink:to="Locator_us-gaap_StockOptionPlanExpense_3384" order="6.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3385" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="Locator_us-gaap_NetIncomeLoss_3386" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3385" xlink:to="Locator_us-gaap_NetIncomeLoss_3386" order="7.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3387" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="Locator_us-gaap_OtherComprehensiveIncomeLossNetOfTax_3388" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3387" xlink:to="Locator_us-gaap_OtherComprehensiveIncomeLossNetOfTax_3388" order="8.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3389" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesIssued" xlink:label="Locator_us-gaap_SharesIssued_3390" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3389" xlink:to="Locator_us-gaap_SharesIssued_3390" order="10.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3391" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_3392" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3391" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_3392" order="11.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3393" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_3394" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3393" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_3394" order="12.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3395" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:label="Locator_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_3396" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3395" xlink:to="Locator_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_3396" order="13.0" />
        <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="Locator_us-gaap_StatementLineItems_3397" />
        <loc xlink:type="locator" xlink:href="hbio-20190630.xsd#hbio_Shareswithheldfortaxesshares" xlink:label="Locator_hbio_Shareswithheldfortaxesshares_3398" />
        <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="Locator_us-gaap_StatementLineItems_3397" xlink:to="Locator_hbio_Shareswithheldfortaxesshares_3398" order="14.0" />
    </definitionLink>
</linkbase>
