-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 LL7J4ijZR4mLLEjIaEqoX05rlh0yabdqXHaqTDYuPh5qRlj7BVoVWwQlJePkAYW8
 +O+wxxAQx+R5w4D6dd6rSQ==

<SEC-DOCUMENT>0001417357-10-000031.txt : 20100128
<SEC-HEADER>0001417357-10-000031.hdr.sgml : 20100128
<ACCEPTANCE-DATETIME>20100128133239
ACCESSION NUMBER:		0001417357-10-000031
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100127
FILED AS OF DATE:		20100128
DATE AS OF CHANGE:		20100128

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Grady Lois W
		CENTRAL INDEX KEY:			0001383375

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33808
		FILM NUMBER:		10553110

	MAIL ADDRESS:	
		STREET 1:		C/O ONEBEACON INSURANCE GROUP, LTD.
		STREET 2:		1 BEACON LANE
		CITY:			CANTON
		STATE:			MA
		ZIP:			02021

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>2010-01-27</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001383375</rptOwnerCik>
            <rptOwnerName>Grady Lois W</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>7000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

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