content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001731462</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001101302</issuerCik>
        <issuerName>ENTEGRIS INC</issuerName>
        <secFileNumber>001-32598</secFileNumber>
        <issuerAddress>
          <com:street1>129 CONCORD ROAD</com:street1>
          <com:city>BILLERICA</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>01821</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>9784366500</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Beckman Bruce W.</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>3253</noOfUnitsSold>
        <aggregateMarketValue>391010.60</aggregateMarketValue>
        <noOfUnitsOutstanding>150158883</noOfUnitsOutstanding>
        <approxSaleDate>12/22/2023</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/11/2022</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1466</amountOfSecuritiesAcquired>
        <paymentDate>02/11/2022</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/19/2022</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1787</amountOfSecuritiesAcquired>
        <paymentDate>02/19/2022</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Bruce W. Beckman</name>
          <address>
            <com:street1>129 Concord Road</com:street1>
            <com:city>Billerica</com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>01821</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>11/13/2023</saleDate>
        <amountOfSecuritiesSold>7840</amountOfSecuritiesSold>
        <grossProceeds>738244.18</grossProceeds>
      </securitiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Bruce W. Beckman</name>
          <address>
            <com:street1>129 Concord Road</com:street1>
            <com:city>Billerica</com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>01821</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>12/04/2023</saleDate>
        <amountOfSecuritiesSold>1838</amountOfSecuritiesSold>
        <grossProceeds>191622.96</grossProceeds>
      </securitiesSoldInPast3Months>
      <remarks>The trade today occurred in the Bruce W Beckman Rev Trust, in which Bruce W Beckman is a trustee.</remarks>
      <noticeSignature>
        <noticeDate>12/22/2023</noticeDate>
        <signature>/s/ Courtney Broxterman, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Bruce W. Beckman</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4658}]
text: 144
  0001731462
  XXXXXXXX
  LIVE
  0001101302
  ENTEGRIS INC
  001-32598
  129 CONCORD ROAD
  BILLERICA
  MA
  01821
  9784366500
  Beckman Bruce W.
  Officer
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  3253
  391010.60
  150158883
  12/22/2023
  NASDAQ
  Common
  02/11/2022
  Restricted Stock Vesting
  Issuer
  N
  1466
  02/11/2022
  Compensation
  Common
  02/19/2022
  Restricted Stock Vesting
  Issuer
  N
  1787
  02/19/2022
  Compensation
  N
  Bruce W. Beckman
  129 Concord Road
  Billerica
  MA
  01821
  Common
  11/13/2023
  7840
  738244.18
  Bruce W. Beckman
  129 Concord Road
  Billerica
  MA
  01821
  Common
  12/04/2023
  1838
  191622.96
  The trade today occurred in the Bruce W Beckman Rev Trust, in which Bruce W Beckman is a trustee.
  12/22/2023
  /s/ Courtney Broxterman, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Bruce W. Beckman