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        <link:definition>9952160 - Disclosure - ACCOUNTING POLICIES</link:definition>
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        <link:definition>9952164 - Disclosure - CREDIT LOSSES</link:definition>
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        <link:definition>9952166 - Disclosure - LEASE COMMITMENTS</link:definition>
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        <link:definition>9952168 - Disclosure - ACCOUNTS PAYABLE, ACCRUED LIABILITIES AND OTHER LONG-TERM LIABILITIES</link:definition>
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        <link:definition>9952169 - Disclosure - DEBT</link:definition>
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        <link:definition>9952173 - Disclosure - EARNINGS PER SHARE</link:definition>
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        <link:definition>9952174 - Disclosure - COMMITMENTS, CONTINGENCIES AND GUARANTEES</link:definition>
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        <link:definition>9952175 - Disclosure - SEGMENT REPORTING</link:definition>
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        <link:definition>9952176 - Disclosure - FAIR VALUE MEASUREMENTS</link:definition>
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        <link:definition>9955512 - Disclosure - REVENUE (Tables)</link:definition>
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        <link:definition>9955513 - Disclosure - INVENTORIES (Tables)</link:definition>
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        <link:definition>9955514 - Disclosure - LEASE COMMITMENTS (Tables)</link:definition>
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        <link:definition>9955515 - Disclosure - OTHER CURRENT AND LONG-TERM ASSETS (Tables)</link:definition>
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        <link:definition>9955516 - Disclosure - ACCOUNTS PAYABLE, ACCRUED LIABILITIES AND OTHER LONG-TERM LIABILITIES (Tables)</link:definition>
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        <link:definition>9955517 - Disclosure - DEBT (Tables)</link:definition>
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        <link:definition>9955518 - Disclosure - REPURCHASES OF COMMON STOCK (Tables)</link:definition>
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        <link:definition>9955519 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)</link:definition>
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        <link:definition>9955520 - Disclosure - EARNINGS PER SHARE (Tables)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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        <link:definition>9955521 - Disclosure - SEGMENT REPORTING (Tables)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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        <link:definition>9955522 - Disclosure - FAIR VALUE MEASUREMENTS (Tables)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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        <link:definition>9955523 - Disclosure - HEDGING INSTRUMENTS (Tables)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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        <link:definition>9955524 - Disclosure - REVENUE (Disaggregation of Revenue by Major Product and Service Categories) (Details)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
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        <link:definition>9955525 - Disclosure - REVENUE (Disaggregation of Revenue by Principal Geographic Area, Based on Customers' Domiciles) (Details)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
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        <link:definition>9955526 - Disclosure - REVENUE (Free or Discounted Instruments and Systems) (Details)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
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      <link:roleType id="REVENUEUpFrontConsiderationPaidtoCustomersDetails" roleURI="http://www.idexx.com/role/REVENUEUpFrontConsiderationPaidtoCustomersDetails">
        <link:definition>9955527 - Disclosure - REVENUE (Up-Front Consideration Paid to Customers) (Details)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
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      <link:roleType id="REVENUERebateArrangementsDetails" roleURI="http://www.idexx.com/role/REVENUERebateArrangementsDetails">
        <link:definition>9955528 - Disclosure - REVENUE (Rebate Arrangements) (Details)</link:definition>
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        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
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      <link:roleType id="REVENUERemainingPerformanceObligationDetails" roleURI="http://www.idexx.com/role/REVENUERemainingPerformanceObligationDetails">
        <link:definition>9955529 - Disclosure - REVENUE (Remaining Performance Obligation) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
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  <xs:element id="idxx_FreeOrDiscountedInstrumentsAndSystemsMember" abstract="true" name="FreeOrDiscountedInstrumentsAndSystemsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="idxx_TreasuryStockAcquiredAverageCostPerShareEmployeeSurrenders" abstract="false" name="TreasuryStockAcquiredAverageCostPerShareEmployeeSurrenders" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
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  <xs:element id="idxx_CashFlowHedgeHedgePercentageOfEstimatedExposureFromIntercompanyProductsPurchasesAndSales" abstract="false" name="CashFlowHedgeHedgePercentageOfEstimatedExposureFromIntercompanyProductsPurchasesAndSales" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
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  <xs:element id="idxx_CrossCurrencyInterestRateContractMaturing7312028Member" abstract="true" name="CrossCurrencyInterestRateContractMaturing7312028Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="idxx_CrossCurrencyInterestRateContractMaturing9112032Member" abstract="true" name="CrossCurrencyInterestRateContractMaturing9112032Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
