<?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>0001220020</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
  </headerData>
  <formData>
    <issuerInfo>
      <issuerCik>0000883241</issuerCik>
      <issuerName>SYNOPSYS INC</issuerName>
      <secFileNumber>000-19807</secFileNumber>
      <issuerAddress>
        <com:street1>675 ALMANOR AVE</com:street1>
        <com:city>SUNNYVALE</com:city>
        <com:stateOrCountry>CA</com:stateOrCountry>
        <com:zipCode>94085</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>6505845000</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>VALLEE ROY</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Director</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Charles Schwab Corporation</name>
        <address>
          <com:street1>3000 Schwab Way</com:street1>
          <com:city>Westlake</com:city>
          <com:stateOrCountry>TX</com:stateOrCountry>
          <com:zipCode>76262</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>10000</noOfUnitsSold>
      <aggregateMarketValue>5757000.00</aggregateMarketValue>
      <noOfUnitsOutstanding>152543690</noOfUnitsOutstanding>
      <approxSaleDate>02/27/2024</approxSaleDate>
      <securitiesExchangeName>Nasdaq</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>04/13/2020</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Award</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>1503</amountOfSecuritiesAcquired>
      <paymentDate>04/13/2020</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>04/09/2019</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Award</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>2972</amountOfSecuritiesAcquired>
      <paymentDate>04/09/2019</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>04/02/2014</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Award</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>2232</amountOfSecuritiesAcquired>
      <paymentDate>04/02/2014</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>04/03/2013</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Award</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>1515</amountOfSecuritiesAcquired>
      <paymentDate>04/03/2013</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>04/03/2013</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Award</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>1343</amountOfSecuritiesAcquired>
      <paymentDate>04/03/2013</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>04/03/2013</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Award</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>435</amountOfSecuritiesAcquired>
      <paymentDate>04/03/2013</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <remarks>Registration - RCV Holdings LLC / Roy Vallee, authorized agent</remarks>
    <noticeSignature>
      <noticeDate>02/27/2024</noticeDate>
      <signature>Roy Vallee</signature>
    </noticeSignature>
  </formData>
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144
0001220020
XXXXXXXX
LIVE
0000883241
SYNOPSYS INC
000-19807
675 ALMANOR AVE
SUNNYVALE
CA
94085
6505845000
VALLEE ROY
Director
Common
Charles Schwab Corporation
3000 Schwab Way
Westlake
TX
76262
10000
5757000.00
152543690
02/27/2024
Nasdaq
Common
04/13/2020
Restricted Stock Award
Issuer
N
1503
04/13/2020
Compensation
Common
04/09/2019
Restricted Stock Award
Issuer
N
2972
04/09/2019
Compensation
Common
04/02/2014
Restricted Stock Award
Issuer
N
2232
04/02/2014
Compensation
Common
04/03/2013
Restricted Stock Award
Issuer
N
1515
04/03/2013
Compensation
Common
04/03/2013
Restricted Stock Award
Issuer
N
1343
04/03/2013
Compensation
Common
04/03/2013
Restricted Stock Award
Issuer
N
435
04/03/2013
Compensation
Y
Registration - RCV Holdings LLC / Roy Vallee, authorized agent
02/27/2024
Roy Vallee