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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 GuG9yYiKSfIifjWTsgobJt+zdu/pia1aU0WCSUp93Vj/z0GchWOI8ddLolcuKVse
 FcoKY9eJNI75HkpRPmydRQ==

<SEC-DOCUMENT>0001031296-03-000226.txt : 20031010
<SEC-HEADER>0001031296-03-000226.hdr.sgml : 20031010
<ACCEPTANCE-DATETIME>20031010111831
ACCESSION NUMBER:		0001031296-03-000226
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031009
FILED AS OF DATE:		20031010

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HEISLER ROBERT B JR
		CENTRAL INDEX KEY:			0001127147

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	333-21011
		FILM NUMBER:		03936402

	BUSINESS ADDRESS:	
		STREET 1:		C/O FIRSTENERGY CORP
		STREET 2:		76 SOUTH MAIN STREET
		CITY:			AKRON
		STATE:			OH
		ZIP:			44308
		BUSINESS PHONE:		3307614264

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FIRSTENERGY CORP
		CENTRAL INDEX KEY:			0001031296
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC SERVICES [4911]
		IRS NUMBER:				341843785
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		76 SOUTH MAIN ST
		CITY:			AKRON
		STATE:			OH
		ZIP:			44308-1890
		BUSINESS PHONE:		3303845100

	MAIL ADDRESS:	
		STREET 1:		76 SOUTH MAIN ST
		CITY:			AKRON
		STATE:			OH
		ZIP:			44308-1890
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>c0001127147d20031010f4f.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-10-09</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0001031296</issuerCik><issuerName>FIRSTENERGY CORP</issuerName>        <issuerTradingSymbol>FE</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001127147</rptOwnerCik><rptOwnerName>HEISLER ROBERT B JR</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>76 SOUTH MAIN STREET</rptOwnerStreet1><rptOwnerStreet2></rptOwnerStreet2><rptOwnerCity>AKRON</rptOwnerCity><rptOwnerState>OH</rptOwnerState><rptOwnerZipCode>44308</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle></officerTitle><otherText></otherText></reportingOwnerRelationship></reportingOwner><nonDerivativeTable></nonDer
ivativeTable><derivativeTable><derivativeHolding><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>31.69</value></conversionOrExercisePrice><exerciseDate><value>2005-01-01</value></exerciseDate><expirationDate><value>2011-01-01</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5096</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>5096</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Stock Options (Right to buy)</value></securityTitle><conversionOrExercisePrice><value>31.7438</value></conversionOrExercisePrice><exerciseDate><value>2003-01-01</valu
e></exerciseDate><expirationDate><value>2009-01-01</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5110</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>5110</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeHolding><derivativeTransaction><securityTitle><value>Phantom Stock Units</value></securityTitle><conversionOrExercisePrice><value>1</value><footnoteId id="F1"/></conversionOrExercisePrice><transactionDate><value>2003-10-09</value></transactionDate><deemedExecutionDate><value>2003-10-09</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapIn
volved></transactionCoding><transactionAmounts><transactionShares><value>69</value></transactionShares><transactionPricePerShare><value>32.74</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1988-08-08</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>1988-08-08</value><footnoteId id="F2"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>69</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>13062.9508</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By State Street</value></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeTransaction><securityTitle><value>Phantom Stock U
nits</value></securityTitle><conversionOrExercisePrice><value>1</value><footnoteId id="F1"/></conversionOrExercisePrice><transactionDate><value>2003-10-09</value></transactionDate><deemedExecutionDate><value>2003-10-09</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>306</value></transactionShares><transactionPricePerShare><value>32.76</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1988-08-08</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>1988-08-08</value><footnoteId id="F2"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>306</value></underlyingSecurityShares></underlyingSecurity><postTransaction
Amounts><sharesOwnedFollowingTransaction><value>13368.9508</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By State Street</value></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">1 for 1</footnote><footnote id="F2">In accordance with the terms and conditions of the FirstEnergy Corp. Deferred Compensation plan for Outside Directors.</footnote></footnotes><ownerSignature><signatureName>David W. Whitehead, POA</signatureName><signatureDate>2003-10-10</signatureDate></ownerSignature></ownershipDocument>

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