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>0001995110</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001049521</issuerCik>
        <issuerName>MERCURY SYSTEMS INC</issuerName>
        <secFileNumber>001-41194</secFileNumber>
        <issuerAddress>
          <com:street1>50 MINUTEMAN ROAD</com:street1>
          <com:city>ANDOVER</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>01810</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>9782561300</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Ratner Steven</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>2202</noOfUnitsSold>
        <aggregateMarketValue>61134.35</aggregateMarketValue>
        <noOfUnitsOutstanding>59345998</noOfUnitsOutstanding>
        <approxSaleDate>06/18/2024</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>06/14/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>2202</amountOfSecuritiesAcquired>
        <paymentDate>06/14/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <remarks>Sale includes an amount necessary to cover a tax obligation resulting from the settlement of a vested equity award distribution.</remarks>
      <noticeSignature>
        <noticeDate>06/18/2024</noticeDate>
        <signature>/s/ Eric Janiak, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Steven V. Ratner</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 2976}]
text: 144
  0001995110
  XXXXXXXX
  LIVE
  0001049521
  MERCURY SYSTEMS INC
  001-41194
  50 MINUTEMAN ROAD
  ANDOVER
  MA
  01810
  9782561300
  Ratner Steven
  Officer
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  2202
  61134.35
  59345998
  06/18/2024
  NASDAQ
  Common
  06/14/2024
  Restricted Stock Vesting
  Issuer
  N
  2202
  06/14/2024
  Compensation
  Y
  Sale includes an amount necessary to cover a tax obligation resulting from the settlement of a vested equity award distribution.
  06/18/2024
  /s/ Eric Janiak, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Steven V. Ratner