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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 SCNa59O+eN2BCsvJCNYiUFCVdGHx1pta2Sba25rNrRDg8acYSrk198k/ORW57eSV
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<SEC-DOCUMENT>0001417357-10-000061.txt : 20100819
<SEC-HEADER>0001417357-10-000061.hdr.sgml : 20100819
<ACCEPTANCE-DATETIME>20100819141414
ACCESSION NUMBER:		0001417357-10-000061
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100817
FILED AS OF DATE:		20100819
DATE AS OF CHANGE:		20100819

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BURGESS PETER S
		CENTRAL INDEX KEY:			0001278907

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33808
		FILM NUMBER:		101027615

	MAIL ADDRESS:	
		STREET 1:		88 SHERWOOD DRIVE
		CITY:			GLASTONBURY
		STATE:			CT
		ZIP:			06033

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
</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>2010-08-17</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001278907</rptOwnerCik>
            <rptOwnerName>BURGESS PETER S</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>2010-08-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.428</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2000</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighted average price.  These shares were purchased in multiple trasactions at prices ranging from $10.428 to $10.429, inclusive.  The reporting person undertakes to provide Symetra Financial Corp., any security holder of Symetra Financial Corp., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (1) to this Form 4.</footnote>
        <footnote id="F2">Includes 2,000 shares held by Peter Burgess IRA.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jacqueline M. Veneziani, Attorney in fact</signatureName>
        <signatureDate>2010-08-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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