-----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,
 S1soC5M38TP/Xd8kZyoSKXdgVHFv9w30sCgS/lbo5Y6GmC3h1Tc2ixFR48uchftq
 2UD8GtE5aRy5vX87Bf2yNA==

<SEC-DOCUMENT>0001123292-10-000525.txt : 20100614
<SEC-HEADER>0001123292-10-000525.hdr.sgml : 20100614
<ACCEPTANCE-DATETIME>20100614172357
ACCESSION NUMBER:		0001123292-10-000525
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100611
FILED AS OF DATE:		20100614
DATE AS OF CHANGE:		20100614

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kruger Jan
		CENTRAL INDEX KEY:			0001382988

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24931
		FILM NUMBER:		10895657

	MAIL ADDRESS:	
		STREET 1:		C/O S1 CORPORATION
		STREET 2:		3500 LENOX RD., SUITE 200
		CITY:			ATLANTA
		STATE:			GA
		ZIP:			30326

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			S1 CORP /DE/
		CENTRAL INDEX KEY:			0001063254
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER PROGRAMMING, DATA PROCESSING, ETC. [7370]
		IRS NUMBER:				582395199
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		705 WESTECH DRIVE
		CITY:			NORCROSS
		STATE:			GA
		ZIP:			30092
		BUSINESS PHONE:		4049233500

	MAIL ADDRESS:	
		STREET 1:		705 WESTECH DRIVE
		CITY:			NORCROSS
		STATE:			GA
		ZIP:			30092

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SECURITY FIRST TECHNOLOGIES CORP
		DATE OF NAME CHANGE:	19980603
</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>2010-06-11</periodOfReport>

    <issuer>
        <issuerCik>0001063254</issuerCik>
        <issuerName>S1 CORP /DE/</issuerName>
        <issuerTradingSymbol>SONE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001382988</rptOwnerCik>
            <rptOwnerName>Kruger Jan</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O S1 CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>705 WESTECH DRIVE</rptOwnerStreet2>
            <rptOwnerCity>NORCROSS</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30092</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Group President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-06-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4057</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.18</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>95576</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ R. Daniel Keating, Attorney-in-Fact</signatureName>
        <signatureDate>2010-06-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----