<SUBMISSION>
<ACCESSION-NUMBER>0001056916-04-000002
<TYPE>5
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20031231
<FILING-DATE>20040115
<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>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>WEYERHAEUSER WILLIAM T
<CIK>0001056916
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>5
<ACT>34
<FILE-NUMBER>000-20288
<FILM-NUMBER>04526606
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>P O BOX 1278
<CITY>TACOMA
<STATE>WA
<ZIP>98401
<PHONE>2532728336
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>PO BOX 1278
<CITY>TACOMA
<STATE>WA
<ZIP>98401
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>5
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>5</documentType><periodOfReport>2003-12-31</periodOfReport>
    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000887343</issuerCik>
        <issuerName>COLUMBIA BANKING SYSTEM INC</issuerName>
        <issuerTradingSymbol>COLB</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001056916</rptOwnerCik>
            <rptOwnerName>WEYERHAEUSER WILLIAM T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1301 A STREET, STE. 800, MS-3100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>TACOMA</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98402-4200</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>NQSO (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>15.12</value></conversionOrExercisePrice><transactionDate><value>2003-04-23</value></transactionDate><transactionCoding><transactionFormType>5</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>1000</value></transactionShares><transactionPricePerShare><footnoteId id="F1"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2006-04-23</value></exerciseDate><expirationDate><value>2011-04-23</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>8567</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">This is a Non-qualified stock option grant.  No other price is relevant here.</footnote></footnotes><remarks/><ownerSignature><signatureName>Kristy W. House</signatureName><signatureDate>2004-01-15</signatureDate></ownerSignature></ownershipDocument>

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