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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-10-09</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001415515</rptOwnerCik>
            <rptOwnerName>Fluegel Bradley M</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>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Walgreen Co. Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-10-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8983</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9630</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 9, 2013, the Compensation Committee determined that the the performance criteria applicable to this restricted stock unit award granted on November 1, 2012 (not a derivative security within the meaning of Rule 16a-1(c) upon grant) under the Walgreen Co. Long-Term Performance 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, 2015, 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, 2013) on outstanding restricted stock units and shares acquired pursuant to employee stock purchase plan, including 245 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>2013-10-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2013-10-09
0000104207
WALGREEN CO
WAG
0001415515
Fluegel Bradley M
WALGREEN CO.
108 WILMOT ROAD
DEERFIELD
IL
60015
0
1
0
0
Senior Vice President
Walgreen Co. Common Stock
2013-10-09
4
A
0
8983
0
A
9630
D
On October 9, 2013, the Compensation Committee determined that the the performance criteria applicable to this restricted stock unit award granted on November 1, 2012 (not a derivative security within the meaning of Rule 16a-1(c) upon grant) under the Walgreen Co. Long-Term Performance 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, 2015, subject to the terms and conditions of the Plan.
Includes shares underlying restricted stock units issued in lieu of dividends (through September 12, 2013) on outstanding restricted stock units and shares acquired pursuant to employee stock purchase plan, including 245 shares with respect to the restricted stock unit award described in note (1) above.
/s/ Mark L. Dosier, Attorney-in-Fact
2013-10-10