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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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<SEC-DOCUMENT>0001276465-04-000026.txt : 20040507
<SEC-HEADER>0001276465-04-000026.hdr.sgml : 20040507
<ACCEPTANCE-DATETIME>20040507144706
ACCESSION NUMBER:		0001276465-04-000026
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040505
FILED AS OF DATE:		20040507

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ALLMERICA FINANCIAL CORP
		CENTRAL INDEX KEY:			0000944695
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		IRS NUMBER:				043263626
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		440 LINCOLN ST
		CITY:			WORCESTER
		STATE:			MA
		ZIP:			01653
		BUSINESS PHONE:		5088551000

	MAIL ADDRESS:	
		STREET 1:		440 LINCOLN ST
		CITY:			WORCESTER
		STATE:			MA
		ZIP:			01653

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KNOX WENDELL J
		CENTRAL INDEX KEY:			0001227468

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13754
		FILM NUMBER:		04788652

	BUSINESS ADDRESS:	
		STREET 1:		4 LAUREN DR.
		CITY:			LINCOLN
		STATE:			MA
		ZIP:			01773
		BUSINESS PHONE:		7812590098

	MAIL ADDRESS:	
		STREET 1:		4 LAUREN DR
		CITY:			LINCOLN
		STATE:			MA
		ZIP:			01733
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-05-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000944695</issuerCik>
        <issuerName>ALLMERICA FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>AFC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001227468</rptOwnerCik>
            <rptOwnerName>KNOX WENDELL J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4 LAUREL DR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LINCOLN</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01733</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-05-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4485</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Deferral Agreement</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares granted as portion of annual retainer fee pursuant to Issuer's Amended and Restated Non-Employee Director Stock Ownership Plan.</footnote>
        <footnote id="F2">4,204 shares of Common Stock held directly, following reported transaction.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Charles F. Cronin, pursuant to Confirming Statement</signatureName>
        <signatureDate>2004-05-07</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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