<?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>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, Ops &amp; Community Mgt</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>17941</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>155026</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <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="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>19883</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>174909</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Walgreen Co. Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-10-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>9336</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>55.01</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>165573</value>
                    <footnoteId id="F4"/>
                </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 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">Shares issued upon settlement of peformance share award (not a derivative security within the meaning of Rule 16a-1(c)) granted on September 1, 2010 under the Plan.</footnote>
        <footnote id="F3">Disposition relating to the satisfaction of tax withholding obligations upon the settlement of performance share award granted in accordance with Rule 16b-3.</footnote>
        <footnote id="F4">Includes shares underlying restricted stock units issued in lieu of dividends (through September 12, 2013) on outstanding restricted stock units, including 490 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
0001188858
WAGNER MARK A
108 WILMOT ROAD
DEERFIELD
IL
60015
0
1
0
0
President, Ops & Community Mgt
Walgreen Co. Common Stock
2013-10-09
4
A
0
17941
0
A
155026
D
Walgreen Co. Common Stock
2013-10-09
4
A
0
19883
0
A
174909
D
Walgreen Co. Common Stock
2013-10-09
4
F
0
9336
55.01
D
165573
D
Walgreen Co. Common Stock
587
I
By spouse
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.
Shares issued upon settlement of peformance share award (not a derivative security within the meaning of Rule 16a-1(c)) granted on September 1, 2010 under the Plan.
Disposition relating to the satisfaction of tax withholding obligations upon the settlement of performance share award granted in accordance with Rule 16b-3.
Includes shares underlying restricted stock units issued in lieu of dividends (through September 12, 2013) on outstanding restricted stock units, including 490 shares with respect to the restricted stock unit award described in note (1) above.
/s/ Mark L. Dosier, attorney-in-fact
2013-10-10