-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 OY+QjZphGIoAMJKti8+ngH1YOBCE/eGal6sDclL6jfEcJux6sANFMnyYym24sUnn
 etT/jempjLXEWsrkZPcj3Q==

<SEC-DOCUMENT>0001103963-04-000001.txt : 20040106
<SEC-HEADER>0001103963-04-000001.hdr.sgml : 20040106
<ACCEPTANCE-DATETIME>20040106114943
ACCESSION NUMBER:		0001103963-04-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040102
FILED AS OF DATE:		20040106

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CADENCE DESIGN SYSTEMS INC
		CENTRAL INDEX KEY:			0000813672
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				770148231
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0102

	BUSINESS ADDRESS:	
		STREET 1:		2655 SEELY ROAD BLDG 5
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95134
		BUSINESS PHONE:		4089431234

	MAIL ADDRESS:	
		STREET 1:		555 RIVER OAKS PARKWAY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95134

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ECAD INC /DE/
		DATE OF NAME CHANGE:	19880609

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			LEV LAVI
		CENTRAL INDEX KEY:			0001103963

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10606
		FILM NUMBER:		04508509

	BUSINESS ADDRESS:	
		STREET 1:		C/O MIPS TECHNOLOGIES INC
		STREET 2:		1225 CHARLESTON ROAD
		CITY:			MOUNTAIN VIEW
		STATE:			CA
		ZIP:			94043
		BUSINESS PHONE:		6509331440

	MAIL ADDRESS:	
		STREET 1:		C/O CANDENCE DESIGN SYSTEM INC
		STREET 2:		2655 SEELY AVE
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95134
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2004-01-02</periodOfReport>
    <issuer>
        <issuerCik>0000813672</issuerCik>
        <issuerName>CADENCE DESIGN SYSTEMS INC</issuerName>
        <issuerTradingSymbol>CDN</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001103963</rptOwnerCik>
            <rptOwnerName>LEV LAVI</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2655 SEELY AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95134</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>EVP and General Manager</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2004-01-02</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10000</value></transactionShares><transactionPricePerShare><value>9.735</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwner
ship><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2004-01-02</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>S</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>10000</value></transactionShares><transactionPricePerShare><value>18.10</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><derivativeTable><derivativeTr
ansaction><securityTitle><value>Employee Stock Option (right to buy)</value></securityTitle><conversionOrExercisePrice><value>9.735</value></conversionOrExercisePrice><transactionDate><value>2004-01-02</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F2"/></exerciseDate><expirationDate><value>2013-02-14</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>10000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>210000</value></sha
resOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on October 22, 2003.</footnote><footnote id="F2">Option was granted on 2/14/2003 and vests at the rate of 1/48th monthly commencing on date of grant.</footnote></footnotes><remarks/><ownerSignature><signatureName>R.L. Smith McKeithen, Attorney-in-Fact for Lavi Lev</signatureName><signatureDate>2004-01-05</signatureDate></ownerSignature></ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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