<SUBMISSION>
<ACCESSION-NUMBER>0000899171-03-000066
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20030618
<FILING-DATE>20030619
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>ECKROTE DOUGLAS E
<CIK>0001215329
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-21796
<FILM-NUMBER>03749380
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>4484 NORMANDY CT
<CITY>LONG GROVE
<STATE>IL
<ZIP>60047
<PHONE>8474656000
</BUSINESS-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>CDW CORP
<CIK>0000899171
<ASSIGNED-SIC>5961
<IRS-NUMBER>363310735
<STATE-OF-INCORPORATION>IL
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>200 N MILWAUKEE AVE
<CITY>VERNON HILLS
<STATE>IL
<ZIP>60061
<PHONE>8474656000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>200 N MILWAUKEE AVE
<CITY>VERNON HILLS
<STATE>IL
<ZIP>60061
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>CDW COMPUTER CENTERS INC
<DATE-CHANGED>19930322
</FORMER-COMPANY>
</ISSUER>
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<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-06-18</periodOfReport>
    <issuer>
        <issuerCik>0000899171</issuerCik>
        <issuerName>CDW CORP</issuerName>
        <issuerTradingSymbol>CDWC</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001215329</rptOwnerCik>
            <rptOwnerName>ECKROTE DOUGLAS E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Senior VP - Purchasing and Ops</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeSecurity><securityTitle><value>Common Stock, $.01 par value</value></securityTitle><transactionDate><value>2003-06-18</value></transactionDate><transactionCoding><transactionFormType>5</transactionFormType><transactionCode>S</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>3000</value></transactionShares><transactionValue><value>43.48</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>31583</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><footnotes/><ownerSignature><signatureName>Douglas E. Eckrote</signatureName><signatureDate>2003-06-18</signatureDate></ownerSignature></ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
