May 23, 1995
                                                      Exhibit 5.1

Osmonics, Inc. 
5951 Clearwater Drive 
Minnetonka, MN  55343

     Re:  Registration Statement on Form S-8

Ladies and Gentlemen:

    We have acted on behalf of Osmonics, Inc. (the "Company") in connection
with a Registration Statement on Form S-8 filed by the Company with the
Securities and Exchange Commission (the "Registration Statement"), 
relating to 400,000 shares of Common Stock, $0.01 par value (the "Shares")
to be issued by the Company pursuant to the terms of the Osmonics, Inc.
1995 Employee Stock Purchase Plan (the "Employee Plan").  Upon 
examination of such corporate documents and records as we have deemed 
necessary or advisable for the purposes hereof and including and in reliance
upon certain certificates by the Company, it is our opinion that:

     1.   The Company is a validly existing corporation in good standing under 
the laws of the State of Minnesota.

     2.   The Shares, when issued and paid for as contemplated by the
Employee Plan, and when delivered against payment therefor in the 
manner contemplated by the Employee Plan, will be validly issued, fully 
paid and non-assessable.

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

                         Very truly yours,


                         MASLON EDELMAN BORMAN & BRAND, 
                         a Professional Limited Liability Partnership