<SUBMISSION>
<ACCESSION-NUMBER>0001186651-07-000001
<TYPE>4/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20060731
<FILING-DATE>20070820
<DATE-OF-FILING-DATE-CHANGE>20070820
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>MATSON TOM SR
<CIK>0001186651
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4/A
<ACT>34
<FILE-NUMBER>000-20288
<FILM-NUMBER>071067081
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>1301 A STREET
<STREET2>MS 3100
<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/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2006-07-31</periodOfReport>

    <dateOfOriginalSubmission>2006-07-31</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000887343</issuerCik>
        <issuerName>COLUMBIA BANKING SYSTEM INC</issuerName>
        <issuerTradingSymbol>COLB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001186651</rptOwnerCik>
            <rptOwnerName>MATSON TOM SR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1301 A STREET, STE. 800, MS-3100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>TACOMA</rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode>98402-4200</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2007-08-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>64788</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>32.74</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>66439</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Cathleen Dent</signatureName>
        <signatureDate>2007-08-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
