-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 I5fcUz2hT3xxgMihAsU4dDmQ71YBjQsVTimmAApXd2wbmA5+8nolRJEcl4JshRLd
 Rgfmi6jxStKa+w0IpbEoZw==

<SEC-DOCUMENT>0001179110-05-013553.txt : 20050701
<SEC-HEADER>0001179110-05-013553.hdr.sgml : 20050701
<ACCEPTANCE-DATETIME>20050701164034
ACCESSION NUMBER:		0001179110-05-013553
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050630
FILED AS OF DATE:		20050701
DATE AS OF CHANGE:		20050701

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			JOHNSON JOEL W
		CENTRAL INDEX KEY:			0001190003

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09328
		FILM NUMBER:		05933813

	BUSINESS ADDRESS:	
		STREET 1:		1 HORMEL PLACE
		CITY:			AUSTIN
		STATE:			MN
		ZIP:			55912

	MAIL ADDRESS:	
		STREET 1:		1 HORMEL PLACE
		CITY:			AUSTIN
		STATE:			TX
		ZIP:			55912

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ECOLAB INC
		CENTRAL INDEX KEY:			0000031462
		STANDARD INDUSTRIAL CLASSIFICATION:	SOAP, DETERGENT, CLEANING PREPARATIONS, PERFUMES, COSMETICS [2840]
		IRS NUMBER:				410231510
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		ECOLAB CTR
		STREET 2:		370 WABASHA ST NORTH
		CITY:			ST PAUL
		STATE:			MN
		ZIP:			55102
		BUSINESS PHONE:		6512932233

	MAIL ADDRESS:	
		STREET 1:		370 WABASHA ST NORTH
		CITY:			ST. PAUL
		STATE:			MN
		ZIP:			55102

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ECONOMICS LABORATORY INC
		DATE OF NAME CHANGE:	19861203
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-06-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000031462</issuerCik>
        <issuerName>ECOLAB INC</issuerName>
        <issuerTradingSymbol>ECL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190003</rptOwnerCik>
            <rptOwnerName>JOHNSON JOEL W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>HORMEL FOODS CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>1 HORMEL PLACE</rptOwnerStreet2>
            <rptOwnerCity>AUSTIN</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55912-3680</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-06-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>194.07</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22571.99</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-06-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>426.95</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>32.205</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>23058.87</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 4.502 shares acquired by dividend reinvestment under the Dividend Reinvestment and Stock Purchase Plan for shareholders of Ecolab sponsored by Computershare Trust Company, Inc. and 51.00 shares acquired pursuant to a dividend reinvestment feature of the Ecolab Inc. 2001 Non-Employee Director Stock Option and Deferred Compensation Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ David F. Duvick, Attorney-in-Fact for Joel W. Johnson</signatureName>
        <signatureDate>2005-07-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----