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        <link:definition>2412402 - Disclosure - Leases (Maturities of Operating Lease Liabilities) (Details)</link:definition>
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      <link:roleType id="LeasesSupplementalCashFlowInformationDetails" roleURI="http://www.idexx.com/role/LeasesSupplementalCashFlowInformationDetails">
        <link:definition>2412404 - Disclosure - Leases (Supplemental Cash Flow Information) (Details)</link:definition>
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        <link:definition>2113100 - Disclosure - Other Current and Long-Term Assets</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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      <link:roleType id="OtherCurrentAndLongTermAssetsScheduleOfOtherCurrentAssetsDetails" roleURI="http://www.idexx.com/role/OtherCurrentAndLongTermAssetsScheduleOfOtherCurrentAssetsDetails">
        <link:definition>2413402 - Disclosure - Other Current and Long-Term Assets (Schedule Of Other Current Assets) (Details)</link:definition>
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      <link:roleType id="OtherCurrentAndLongTermAssetsScheduleOfOtherLongTermAssetsDetails" roleURI="http://www.idexx.com/role/OtherCurrentAndLongTermAssetsScheduleOfOtherLongTermAssetsDetails">
        <link:definition>2413403 - Disclosure - Other Current and Long-Term Assets (Schedule Of Other Long-term Assets) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
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      <link:roleType id="OtherCurrentAndLongTermAssetsTables" roleURI="http://www.idexx.com/role/OtherCurrentAndLongTermAssetsTables">
        <link:definition>2313301 - Disclosure - Other Current and Long-Term Assets (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
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      <link:roleType id="RepurchasesOfCommonStock" roleURI="http://www.idexx.com/role/RepurchasesOfCommonStock">
        <link:definition>2116100 - Disclosure - Repurchases Of Common Stock</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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      <link:roleType id="RepurchasesOfCommonStockDetails" roleURI="http://www.idexx.com/role/RepurchasesOfCommonStockDetails">
        <link:definition>2416402 - Disclosure - Repurchases of Common Stock (Details)</link:definition>
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      <link:roleType id="RepurchasesOfCommonStockTables" roleURI="http://www.idexx.com/role/RepurchasesOfCommonStockTables">
        <link:definition>2316301 - Disclosure - Repurchases of Common Stock (Tables)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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      <link:roleType id="RevenueRecognition" roleURI="http://www.idexx.com/role/RevenueRecognition">
        <link:definition>2103100 - Disclosure - Revenue Recognition</link:definition>
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      <link:roleType id="RevenueRecognitionCostsToObtainContractDetails" roleURI="http://www.idexx.com/role/RevenueRecognitionCostsToObtainContractDetails">
        <link:definition>2403413 - Disclosure - Revenue Recognition (Costs to Obtain a Contract) (Details)</link:definition>
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        <link:definition>2403411 - Disclosure - Revenue Recognition (Disaggregation of Revenue by Major Product and Service Categories) (Details)</link:definition>
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        <link:definition>2403412 - Disclosure - Revenue Recognition (Disaggregation of Revenue by Principal Geographic Area, Based on Customers' Domiciles) (Details)</link:definition>
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        <link:definition>2403404 - Disclosure - Revenue Recognition (Extended Warranties and Post-Contract Support) (Details)</link:definition>
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        <link:definition>2403409 - Disclosure - Revenue Recognition (Instrument Rebate Programs) (Details)</link:definition>
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      <link:roleType id="RevenueRecognitionLeaseRevenueDetails" roleURI="http://www.idexx.com/role/RevenueRecognitionLeaseRevenueDetails">
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        <link:definition>2403407 - Disclosure - Revenue Recognition (Up-Front Customer Loyalty Programs) (Details)</link:definition>
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        <link:definition>2403408 - Disclosure - Revenue Recognition (Volume Commitment Programs) (Details)</link:definition>
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        <link:definition>2121100 - Disclosure - Segment Reporting</link:definition>
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      <link:roleType id="SegmentReportingAllocatedCostsDetails" roleURI="http://www.idexx.com/role/SegmentReportingAllocatedCostsDetails">
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        <link:definition>2421403 - Disclosure - Segment Reporting - Summary of Segment Performance (Details)</link:definition>
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        <link:definition>2105100 - Disclosure - Share-Based Compensation</link:definition>
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        <link:definition>2405403 - Disclosure - Share-Based Compensation (Assumptions Used) (Details)</link:definition>
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        <link:definition>2405402 - Disclosure - Share-Based Compensation (Narrative) (Details)</link:definition>
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        <link:definition>2305301 - Disclosure - Share-Based Compensation (Tables)</link:definition>
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        <link:definition>2424401 - Disclosure - Subsequent Events (Details)</link:definition>
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        <link:definition>2124100 - Disclosure - Subsequent Events (Notes)</link:definition>
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  <xsd:element id="idxx_OperatingLeaseLeaseNotyetCommencedExpense" name="OperatingLeaseLeaseNotyetCommencedExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="idxx_OperatingtypeReagentRentalProgramsMember" name="OperatingtypeReagentRentalProgramsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_OtherComprehensiveIncomeLossCashFlowHedgeAndNetInvestmentHedgeGainLossAfterReclassificationAndTax" name="OtherComprehensiveIncomeLossCashFlowHedgeAndNetInvestmentHedgeGainLossAfterReclassificationAndTax" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="idxx_OtherComprehensiveIncomeLossNetInvestmentHedgeCrossCurrencySwapsGainLossBeforeReclassificationAfterTax" name="OtherComprehensiveIncomeLossNetInvestmentHedgeCrossCurrencySwapsGainLossBeforeReclassificationAfterTax" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="idxx_OtherComprehensiveIncomeLossNetInvestmentHedgeCrossCurrencySwapsGainLossBeforeReclassificationTax" name="OtherComprehensiveIncomeLossNetInvestmentHedgeCrossCurrencySwapsGainLossBeforeReclassificationTax" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="idxx_OtherComprehensiveIncomeLossNetInvestmentHedgeEuroDenominatedNotesGainLossAfterReclassificationAndTax" name="OtherComprehensiveIncomeLossNetInvestmentHedgeEuroDenominatedNotesGainLossAfterReclassificationAndTax" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="idxx_OtherComprehensiveIncomeLossNetInvestmentHedgeEuroDenominatedNotesGainLossAfterReclassificationTax" name="OtherComprehensiveIncomeLossNetInvestmentHedgeEuroDenominatedNotesGainLossAfterReclassificationTax" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="idxx_OtherSegmentMember" name="OtherSegmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_PostContractSupportContractTerm" name="PostContractSupportContractTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="idxx_Prudential2030SeriesDNotesMember" name="Prudential2030SeriesDNotesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="idxx_PrudentialMember" name="PrudentialMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_RapidAssayProductsMember" name="RapidAssayProductsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_ReagentRentalProgramsMember" name="ReagentRentalProgramsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_ReferenceLaboratoryDiagnosticAndConsultingServicesMember" name="ReferenceLaboratoryDiagnosticAndConsultingServicesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="idxx_ReferenceLaboratoryinMidWestUnitedStatesMember" name="ReferenceLaboratoryinMidWestUnitedStatesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_RevenuePerformanceObligationPaymentTerm" name="RevenuePerformanceObligationPaymentTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_SaasSubscriptionTermOfContract" name="SaasSubscriptionTermOfContract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_SalesTypeLeaseLeaseReceivableReclassifiedToReceivable" name="SalesTypeLeaseLeaseReceivableReclassifiedToReceivable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="idxx_SeriesCSeniorNoteMember" name="SeriesCSeniorNoteMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_TreasuryStockAcquiredAverageCostPerShareEmployeeSurrenders" name="TreasuryStockAcquiredAverageCostPerShareEmployeeSurrenders" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_TreasuryStockAcquiredAverageCostPerShareOpenMarketRepurchase" name="TreasuryStockAcquiredAverageCostPerShareOpenMarketRepurchase" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_TreasuryStockSharesAcquiredNetOfTaxWithholdings" name="TreasuryStockSharesAcquiredNetOfTaxWithholdings" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_TreasuryStockValueAcquiredCostMethodNetOfTaxWithholdings" name="TreasuryStockValueAcquiredCostMethodNetOfTaxWithholdings" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="idxx_UpFrontCustomerLoyaltyProgramsAndVolumeCommitmentProgramsMember" name="UpFrontCustomerLoyaltyProgramsAndVolumeCommitmentProgramsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_UpFrontCustomerLoyaltyProgramsMember" name="UpFrontCustomerLoyaltyProgramsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_VeterinarySoftwareServicesAndDiagnosticImagingSystemsMember" name="VeterinarySoftwareServicesAndDiagnosticImagingSystemsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_VetlabConsumablesMember" name="VetlabConsumablesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_VolumeCommitmentProgramsMember" name="VolumeCommitmentProgramsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="idxx_WaterSegmentMember" name="WaterSegmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="idxx_WeightedAverageSharesOutstandingAbstract" name="WeightedAverageSharesOutstandingAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
</xsd:schema>
