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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 ANLtfUE9dExmTOSuKLm9nQ==

<SEC-DOCUMENT>0000107815-04-000009.txt : 20040106
<SEC-HEADER>0000107815-04-000009.hdr.sgml : 20040106
<ACCEPTANCE-DATETIME>20040106212253
ACCESSION NUMBER:		0000107815-04-000009
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040102
FILED AS OF DATE:		20040106

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KUESTER FREDERICK D
		CENTRAL INDEX KEY:			0001227592

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09057
		FILM NUMBER:		04511630

	MAIL ADDRESS:	
		STREET 1:		1155 PERIMETER CENTER WEST
		CITY:			ATLANTA
		STATE:			GA
		ZIP:			30338

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WISCONSIN ENERGY CORP
		CENTRAL INDEX KEY:			0000783325
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC & OTHER SERVICES COMBINED [4931]
		IRS NUMBER:				391391525
		STATE OF INCORPORATION:			WI
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		231 W MICHIGAN ST
		STREET 2:		P O BOX 2949
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53201
		BUSINESS PHONE:		4142212345

	MAIL ADDRESS:	
		STREET 1:		231 WEST MICHIGAN STREET
		STREET 2:		P O BOX 2949
		CITY:			MILWAUKEE
		STATE:			WI
		ZIP:			53201
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>c0001227592d20040106f4f.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2004-01-02</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0000783325</issuerCik><issuerName>WISCONSIN ENERGY CORP</issuerName>        <issuerTradingSymbol>WEC</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001227592</rptOwnerCik><rptOwnerName>KUESTER FREDERICK D</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>231 WEST MICHIGAN STREET</rptOwnerStreet1><rptOwnerStreet2></rptOwnerStreet2><rptOwnerCity>MILWAUKEE</rptOwnerCity><rptOwnerState>WI</rptOwnerState><rptOwnerZipCode>53203</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Chief Operating Officer WEPCO</officerTitle><otherText></otherText></reportingOwnerRelationship></
reportingOwner><nonDerivativeTable><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>24287</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>6</value><footnoteId id="F2"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>ERSP</value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOr
ExercisePrice><value>33.435</value></conversionOrExercisePrice><transactionDate><value>2004-01-02</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>11960</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2005-01-02</value><footnoteId id="F3"/></exerciseDate><expirationDate><value>2014-01-02</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>11960</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>11960</value></sharesOwnedFollowingTransaction></postTr
ansactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>33.435</value></conversionOrExercisePrice><transactionDate><value>2004-01-02</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>138040</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2005-01-02</value><footnoteId id="F3"/></exerciseDate><expirationDate><value>2014-01-02</value></expirationDate
><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>138040</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>150000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Includes shares acquired pursuant to a dividend  reinvestment feature of WEC's Stock Plus Investment Plan in transactions exempt from Section 16 pursuant to Rule 16a-11.</footnote><footnote id="F2">Includes shares acquired under WEC's Employee Retirement Savings Plan (ERSP) in transactions exempt from Section 16(b) pursuant to Rule 16b-3(c) and exempt from reporting pursuant to Rule 16a-3(f)(1)(i)(B).  The number of shares in the ERSP attributable to any on
e particpant varies with the price of the Common Stock.  The information in this report is based on a plan statement dated as of January 2, 2004.</footnote><footnote id="F3">Options vest in 25% increments annually beginning on the date indicated.</footnote></footnotes><ownerSignature><signatureName>Kristine A. Rappe as Attorney-in-Fact</signatureName><signatureDate>2004-01-06</signatureDate></ownerSignature></ownershipDocument>

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