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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-10-08</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001555096</rptOwnerCik>
            <rptOwnerName>Murphy Dominic</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O WALGREEN CO.</rptOwnerStreet1>
            <rptOwnerStreet2>108 WILMOT ROAD</rptOwnerStreet2>
            <rptOwnerCity>DEERFIELD</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60015</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2014-10-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>345.753</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>61.46</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>345.753</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4272.3</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The phantom stock is issued as non-employee director compensation under the Walgreen Co. 2013 Omnibus Incentive Plan and converts into the cash value of the company's common stock on a one-for-one basis.</footnote>
        <footnote id="F2">To be settled in two installments, the first of which occurs within thirty days following termination of service as a director, and the second, one year after the first settlement date.</footnote>
        <footnote id="F3">Includes phantom stock units issued in lieu of dividends (through September 12, 2014) on outstanding phantom stock units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/  Mark L. Dosier, attorney-in-fact</signatureName>
        <signatureDate>2014-10-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2014-10-08
0000104207
WALGREEN CO
WAG
0001555096
Murphy Dominic
C/O WALGREEN CO.
108 WILMOT ROAD
DEERFIELD
IL
60015
1
0
0
0
Phantom Stock Units
2014-10-08
4
A
0
345.753
61.46
A
Common Stock
345.753
4272.3
D
The phantom stock is issued as non-employee director compensation under the Walgreen Co. 2013 Omnibus Incentive Plan and converts into the cash value of the company's common stock on a one-for-one basis.
To be settled in two installments, the first of which occurs within thirty days following termination of service as a director, and the second, one year after the first settlement date.
Includes phantom stock units issued in lieu of dividends (through September 12, 2014) on outstanding phantom stock units.
/s/  Mark L. Dosier, attorney-in-fact
2014-10-09