EXHIBIT 5.1

                      [Letterhead of Dorsey & Whitney LLP]



                                 August 6, 2002




Donaldson Company, Inc.
1400 West 94th Street
Minneapolis, Minnesota 55431

                  Re: Registration Statement on Form S-8

Ladies and Gentlemen:

                  We have acted as counsel to Donaldson Company, Inc., a
Delaware corporation (the "Company"), in connection with a Registration
Statement on Form S-8 relating to the sale by the Company from time to time of
up to 6,850,000 shares of Common Stock, $5.00 par value, of the Company (the
"Shares"), initially issuable upon the exercise of stock options granted
pursuant to the Donaldson Company, Inc. 2001 Master Stock Incentive Plan (the
"Plan").

                  We have examined such documents and have reviewed such
questions of law as we have considered necessary and appropriate for the
purposes of our opinion set forth below. In rendering our opinion set forth
below, we have assumed the authenticity of all documents submitted to us as
originals, the genuineness of all signatures and the conformity to authentic
originals of all documents submitted to us as copies. As to questions of fact
material to our opinion, we have relied upon certificates of officers of the
Company and of public officials.

                  Based on the foregoing, we are of the opinion that the Shares
have been duly authorized and, upon issuance, delivery and payment therefor in
accordance with the terms of the Plan, will be validly issued, fully paid and
nonassessable.

                  Our opinion expressed above is limited to the laws of the
State of Delaware.

                  We hereby consent to the filing of this opinion as an exhibit
to the Registration Statement.


                                        Very truly yours,


                                        /s/ Dorsey & Whitney LLP

RAR