content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
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      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001520897</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001022079</issuerCik>
        <issuerName>QUEST DIAGNOSTICS INC</issuerName>
        <secFileNumber>001-12215</secFileNumber>
        <issuerAddress>
          <com:street1>500 PLAZA DRIVE</com:street1>
          <com:city>SECAUCUS</com:city>
          <com:stateOrCountry>NJ</com:stateOrCountry>
          <com:zipCode>07094</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>9735202700</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Doherty Catherine T.</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Fidelity Brokerage Services LLC</name>
          <address>
            <com:street1>900 Salem Street</com:street1>
            <com:city>Smithfield</com:city>
            <com:stateOrCountry>RI</com:stateOrCountry>
            <com:zipCode>02917</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>1187</noOfUnitsSold>
        <aggregateMarketValue>149419.56</aggregateMarketValue>
        <noOfUnitsOutstanding>110707293</noOfUnitsOutstanding>
        <approxSaleDate>02/29/2024</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/23/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>635</amountOfSecuritiesAcquired>
        <paymentDate>02/23/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/24/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>552</amountOfSecuritiesAcquired>
        <paymentDate>02/24/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Catherine T. Doherty</name>
          <address>
            <com:street1>500 Plaza Drive</com:street1>
            <com:city>Secaucus</com:city>
            <com:stateOrCountry>NJ</com:stateOrCountry>
            <com:zipCode>07094</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>02/22/2024</saleDate>
        <amountOfSecuritiesSold>821</amountOfSecuritiesSold>
        <grossProceeds>103560.94</grossProceeds>
      </securitiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Catherine T. Doherty</name>
          <address>
            <com:street1>500 Plaza Drive</com:street1>
            <com:city>Secaucus</com:city>
            <com:stateOrCountry>NJ</com:stateOrCountry>
            <com:zipCode>07094</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>02/28/2024</saleDate>
        <amountOfSecuritiesSold>5557</amountOfSecuritiesSold>
        <grossProceeds>703349.49</grossProceeds>
      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>02/29/2024</noticeDate>
        <planAdoptionDates>
          <planAdoptionDate>08/29/2023</planAdoptionDate>
        </planAdoptionDates>
        <signature>/s/ Emily Navaro, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for  Catherine T. Doherty.</signature>
      </noticeSignature>
    </formData>
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text: 144
  0001520897
  XXXXXXXX
  LIVE
  0001022079
  QUEST DIAGNOSTICS INC
  001-12215
  500 PLAZA DRIVE
  SECAUCUS
  NJ
  07094
  9735202700
  Doherty Catherine T.
  Officer
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  1187
  149419.56
  110707293
  02/29/2024
  NYSE
  Common
  02/23/2024
  Restricted Stock Vesting
  Issuer
  N
  635
  02/23/2024
  Compensation
  Common
  02/24/2024
  Restricted Stock Vesting
  Issuer
  N
  552
  02/24/2024
  Compensation
  N
  Catherine T. Doherty
  500 Plaza Drive
  Secaucus
  NJ
  07094
  Common
  02/22/2024
  821
  103560.94
  Catherine T. Doherty
  500 Plaza Drive
  Secaucus
  NJ
  07094
  Common
  02/28/2024
  5557
  703349.49
  02/29/2024
  08/29/2023
  /s/ Emily Navaro, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for  Catherine T. Doherty.