<SUBMISSION>
<ACCESSION-NUMBER>0001202458-04-000001
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20031231
<FILING-DATE>20040107
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>NELSON MARK W
<CIK>0001202458
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-20288
<FILM-NUMBER>04513765
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>1301 A STREET
<CITY>TACOMA
<STATE>WA
<ZIP>98402-4200
</BUSINESS-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>COLUMBIA BANKING SYSTEM INC
<CIK>0000887343
<ASSIGNED-SIC>6022
<IRS-NUMBER>911422237
<STATE-OF-INCORPORATION>WA
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>1102 BROADWAY PLAZA
<CITY>TACOMA
<STATE>WA
<ZIP>98402
<PHONE>2533051900
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>1102 BROADWAY PLAZA
<CITY>TACOMA
<STATE>WA
<ZIP>98402
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
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<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-12-31</periodOfReport>
    <issuer>
        <issuerCik>0000887343</issuerCik>
        <issuerName>COLUMBIA BANKING SYSTEM INC</issuerName>
        <issuerTradingSymbol>COLB</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001202458</rptOwnerCik>
            <rptOwnerName>NELSON MARK W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1301 A STREET, STE. 800</rptOwnerStreet1>
            <rptOwnerStreet2>MS-3100</rptOwnerStreet2>
            <rptOwnerCity>TACOMA</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98402-4200</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Executive Vice President</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-12-31</value></transactionDate><transactionCoding><transactionFormType>5</transactionFormType><transactionCode>I</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>208</value></transactionShares><transactionPricePerShare><value>16.209</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>545</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><footnotes><footnote id="F1">These shares puchased through ESPP 12/31/03.</footnote></footnotes><remarks/><ownerSignature><signatureName>Kristy W. House</signatureName><signatureDate>2004-01-07</signatureDate></ownerSignature></ownershipDocument>

</XML>
</TEXT>
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