<SUBMISSION>
<ACCESSION-NUMBER>0001246360-09-003223
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20091207
<FILING-DATE>20091209
<DATE-OF-FILING-DATE-CHANGE>20091209
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Cooley Thomas A.
<CIK>0001448377
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-10606
<FILM-NUMBER>091231982
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>2655 SEELY AV., BLDG. 5
<CITY>SAN JOSE
<STATE>CA
<ZIP>95134
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>CADENCE DESIGN SYSTEMS INC
<CIK>0000813672
<ASSIGNED-SIC>7372
<IRS-NUMBER>770148231
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1229
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>2655 SEELY ROAD BLDG 5
<CITY>SAN JOSE
<STATE>CA
<ZIP>95134
<PHONE>4089431234
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>555 RIVER OAKS PARKWAY
<CITY>SAN JOSE
<STATE>CA
<ZIP>95134
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>ECAD INC /DE/
<DATE-CHANGED>19880609
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-12-07</periodOfReport>

    <notSubjectToSection16>false</notSubjectToSection16>

    <issuer>
        <issuerCik>0000813672</issuerCik>
        <issuerName>CADENCE DESIGN SYSTEMS INC</issuerName>
        <issuerTradingSymbol>CDNS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001448377</rptOwnerCik>
            <rptOwnerName>Cooley Thomas A.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2655 SEELY AVENUE, BLDG 5</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95134</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>Sr.VP, WFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-12-07</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>793</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.27</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>70422</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-12-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>661</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.99</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>69761</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares withheld to satisfy tax obligations arising out of vesting of restricted stock.</footnote>
        <footnote id="F2">Shares withheld to satisfy tax obligations arising out of vesting of restricted stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James J. Cowie, Attorney-in-Fact for Thomas A. Cooley</signatureName>
        <signatureDate>2009-12-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
