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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,
 D7tm7BzHOwsNYyrXvuvcXaHyQCB7xg2lIGzCBY3PAb+tjddPnnAMtXdct/JOA5cz
 2JKeHX9H9MNjHp57z8ogAQ==

<SEC-DOCUMENT>0001031296-03-000284.txt : 20031219
<SEC-HEADER>0001031296-03-000284.hdr.sgml : 20031219
<ACCEPTANCE-DATETIME>20031219155008
ACCESSION NUMBER:		0001031296-03-000284
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031219
FILED AS OF DATE:		20031219

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:		031065214

	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>c0001127147d20031219f4f.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-12-19</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>2003-12-19</value></transactionDate><deemedExecutionDate><value>2003-12-19</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapIn
volved></transactionCoding><transactionAmounts><transactionShares><value>327</value></transactionShares><transactionPricePerShare><value>34.69</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>327</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>14151.9535</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 te
rms and conditions of the FirstEnergy Corp. Deferred Compensation plan for Outside Directors.</footnote></footnotes><ownerSignature><signatureName>David W. Whitehead, POA</signatureName><signatureDate>2003-12-19</signatureDate></ownerSignature></ownershipDocument>

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