<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-10-07</periodOfReport>

    <issuer>
        <issuerCik>0000104207</issuerCik>
        <issuerName>WALGREEN CO</issuerName>
        <issuerTradingSymbol>WAG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001124182</rptOwnerCik>
            <rptOwnerName>SABATINO THOMAS J JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>WALGREEN CO.</rptOwnerStreet1>
            <rptOwnerStreet2>108 WILMOT ROAD</rptOwnerStreet2>
            <rptOwnerCity>DEERFIELD</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60015</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, General Counsel and CAO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Walgreen Co. Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-10-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12569</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40145</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On October 7, 2014, the Compensation Committee determined that the performance criteria applicable to this restricted stock unit award granted on November 1, 2013 (not a derivative security within the meaning of Rule 16a-1(c) upon grant) under the Walgreen Co. 2013 Omnibus Incentive Plan (together with the related award agreement, the &quot;Plan&quot;) had been satisfied. The shares underlying these restricted stock units will vest on November 1, 2016, subject to the terms and conditions of the Plan.</footnote>
        <footnote id="F2">Includes shares underlying restricted stock units issued in lieu of dividends (through September 12, 2014) on outstanding restricted stock units, including 256 shares with respect to the restricted stock unit award described in note (1) above.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Mark L. Dosier, attorney-in-fact</signatureName>
        <signatureDate>2014-10-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2014-10-07
0000104207
WALGREEN CO
WAG
0001124182
SABATINO THOMAS J JR
WALGREEN CO.
108 WILMOT ROAD
DEERFIELD
IL
60015
0
1
0
0
EVP, General Counsel and CAO
Walgreen Co. Common Stock
2014-10-07
4
A
0
12569
0
A
40145
D
On October 7, 2014, the Compensation Committee determined that the performance criteria applicable to this restricted stock unit award granted on November 1, 2013 (not a derivative security within the meaning of Rule 16a-1(c) upon grant) under the Walgreen Co. 2013 Omnibus Incentive Plan (together with the related award agreement, the "Plan") had been satisfied. The shares underlying these restricted stock units will vest on November 1, 2016, subject to the terms and conditions of the Plan.
Includes shares underlying restricted stock units issued in lieu of dividends (through September 12, 2014) on outstanding restricted stock units, including 256 shares with respect to the restricted stock unit award described in note (1) above.
/s/ Mark L. Dosier, attorney-in-fact
2014-10-08