-----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,
 EGrcZxka6iWivM2ibMycTD8e8nY+bogXdQ1L1DYni4IDLekuY2wWyKkk9PFErIrt
 N6K5tqrzphkeQHoDT7PhKA==

<SEC-DOCUMENT>0000897101-03-000397.txt : 20030509
<SEC-HEADER>0000897101-03-000397.hdr.sgml : 20030509
<ACCEPTANCE-DATETIME>20030508213609
ACCESSION NUMBER:		0000897101-03-000397
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030507
FILED AS OF DATE:		20030509

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SCHWAB LOWELL F
		CENTRAL INDEX KEY:			0001226581

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-07891
		FILM NUMBER:		03688996

	BUSINESS ADDRESS:	
		STREET 1:		C/O DONALDSON CO INC
		STREET 2:		PO BOX 1299
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55440-1299
		BUSINESS PHONE:		9528873631

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			DONALDSON CO INC
		CENTRAL INDEX KEY:			0000029644
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL & COMMERCIAL FANS & BLOWERS & AIR PURIFYING EQUIP [3564]
		IRS NUMBER:				410222640
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0731

	BUSINESS ADDRESS:	
		STREET 1:		1400 W. 94TH ST.
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55431
		BUSINESS PHONE:		6128873131

	MAIL ADDRESS:	
		STREET 1:		1400 W 94TH STREET
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55431
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>schwab.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0101</schemaVersion>

<documentType>4</documentType>

    <periodOfReport>2003-05-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

<issuer>        <issuerCik>0000029644</issuerCik>
        <issuerName>DONALDSON CO INC</issuerName>
<issuerTradingSymbol>DCI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001226581</rptOwnerCik>

            <rptOwnerName>SCHWAB LOWELL F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
<reportingOwnerRelationship>
            <isOfficer>1</isOfficer>

            <officerTitle>Senior VP, Operations</officerTitle>

        </reportingOwnerRelationship>
    </reportingOwner>


    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
        </securityTitle>
        <transactionDate>

            <value>2003-05-07</value>

        </transactionDate>

        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>A</transactionCode>

            <equitySwapInvolved>0</equitySwapInvolved>

        </transactionCoding>

        <transactionTimeliness>

            <value></value>

        </transactionTimeliness>

        <transactionAmounts>
            <transactionShares>
                <value>10.45</value>
             </transactionShares>
            <transactionValue>
                <value>40.19</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>2003</value>
                 <footnoteId id="F1"/>
                 <footnoteId id="F2"/>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>I</value>
            </directOrIndirectOwnership>
            <natureOfOwnership>

            <value>By Benefit Plan Trust</value>

            </natureOfOwnership>

        </ownershipNature>
    </nonDerivativeSecurity>


    <footnotes>
        <footnote id="F1">The reporting person also indirectly holds 12,946 shares in a benefit plan trust.</footnote>
        <footnote id="F2">The reporting person also directly holds 72,913 shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Lowell Schwab /s/ Norman C. Linnell By Power of Attorney</signatureName>
        <signatureDate>2003-05-08</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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