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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Sr06gBkIhhZXETb7Wn8Kws50ifeh/1o8pZGWp94DhOoFatflHcNQtPkJpUz4+WR/
 1z5o4GM03HKZg84slcJ7og==

<SEC-DOCUMENT>0001417357-10-000034.txt : 20100128
<SEC-HEADER>0001417357-10-000034.hdr.sgml : 20100128
<ACCEPTANCE-DATETIME>20100128161924
ACCESSION NUMBER:		0001417357-10-000034
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100127
FILED AS OF DATE:		20100128
DATE AS OF CHANGE:		20100128

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Symetra Financial CORP
		CENTRAL INDEX KEY:			0001403385
		STANDARD INDUSTRIAL CLASSIFICATION:	LIFE INSURANCE [6311]
		IRS NUMBER:				200978027
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		777 108TH AVENUE NE
		STREET 2:		SUITE 1200
		CITY:			BELLEVUE
		STATE:			WA
		ZIP:			98004-5135
		BUSINESS PHONE:		425-256-8000

	MAIL ADDRESS:	
		STREET 1:		777 108TH AVENUE NE
		STREET 2:		SUITE 1200
		CITY:			BELLEVUE
		STATE:			WA
		ZIP:			98004-5135

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FOY DAVID THOMAS
		CENTRAL INDEX KEY:			0001221318
		STATE OF INCORPORATION:			D0
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33808
		FILM NUMBER:		10554198

	MAIL ADDRESS:	
		STREET 1:		C/O WHITE MOUNTAINS INSURANCE GROUP LTD
		STREET 2:		80 SOUTH MAIN STREET
		CITY:			HANOVER
		STATE:			NH
		ZIP:			03755
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-01-27</periodOfReport>

    <issuer>
        <issuerCik>0001403385</issuerCik>
        <issuerName>Symetra Financial CORP</issuerName>
        <issuerTradingSymbol>SYA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001221318</rptOwnerCik>
            <rptOwnerName>FOY DAVID THOMAS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>777 108TH AVE NE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1200</rptOwnerStreet2>
            <rptOwnerCity>BELLEVUE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98004</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>2010-01-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>100000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17400000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By White Mountain Insurance Group</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares owned by affiliates of White Mountains Insurance Group Ltd., of which Mr. Foy is an executive officer.  Mr. Foy disclaims beneficial ownership of all such shares and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or any other purpose.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jacqueline M. Veneziani, Attorney in Fact</signatureName>
        <signatureDate>2010-01-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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