<?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>0001188858</rptOwnerCik>
            <rptOwnerName>WAGNER MARK A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>108 WILMOT ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></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>President, Business Operations</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>13222</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>173566</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Walgreen Co. Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>587</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By spouse</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </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 269 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
0001188858
WAGNER MARK A
108 WILMOT ROAD
DEERFIELD
IL
60015
0
1
0
0
President, Business Operations
Walgreen Co. Common Stock
2014-10-07
4
A
0
13222
0
A
173566
D
Walgreen Co. Common Stock
587
I
By spouse
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 269 shares with respect to the restricted stock unit award described in note (1) above.
/s/ Mark L. Dosier, attorney-in-fact
2014-10-08