EXHIBIT 5.1

               A PARTNERSHIP INCLUDING PROFESSIONAL CORPORATIONS
                              HINSHAW & CULBERTSON


Belleville, Illinois    222 North La Salle Street   San Francisco, California 
Bloomington, Illinois  Chicago, Illinois 60601-1081  Ft. Lauderdale, Florida  
 Champaign, Illinois                                  Jacksonville, Florida   
Crystal Lake, Illinois     312.704.3000                   Miami, Florida      
  Joliet, Illinois            _______                     Tampa, Florida      
  Lisle, Illinois                                        Munster, Indiana     
  Peoria, Illinois         Telefax 312.704.3001       Minneapolis, Minnesota  
 Rockford, Illinois                                    St. Louis, Missouri    
Springfield, Illinois                                  Appleton, Wisconsin    
 Waukegan, Illinois         March 2, 1998             Brookfield, Wisconsin   
                                                      Lake Geneva, Wisconsin  
                                                       Milwaukee, Wisconsin    

Writer's Direct Dial No.                                     File No.
(312) 704-3852                                                764359



VIA FACSIMILE & FEDERAL EXPRESS
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First Midwest Bancorp, Inc.
300 Park Boulevard, Suite 405
P.O. Box 459
Itasca, Illinois 60143-0459

     RE:  REGISTRATION STATEMENT ON FORM S-4

Ladies and Gentlemen:

     You have requested our opinion in connection with the above-referenced
registration statement (the "Registration Statement") for the registration of up
to 9,725,509 shares of Common Stock, $,01 par value per share, of the Company
(the "Shares") in connection with the Company's acquisition of Heritage
Financial Services, Inc.

     In arriving at the opinion expressed below, we have examined the
Registration Statement and such other documents as we have deemed necessary to
enable us to express the opinion hereinafter set forth. In our examination, we
have assumed the authenticity of all documents submitted to us as originals, the
conformity to the original documents of all documents submitted to us as copies,
the genuineness of all signatures on documents reviewed by us and the legal
capacity of natural persons.

     Based upon and subject to the foregoing, we are of the opinion that the
Shares have been duly authorized and, when issued in accordance with the terms
and conditions set forth in the Registration Statement, will be validly issued,
fully paid and non-assessable.

 
First Midwest Bancorp, Inc.
March 2, 1998
Page 2

     We hereby consent to the reference to our firm under the caption "Opinions"
in the Registration Statement and to the use of this opinion as an exhibit to
the Registration Statement.

                                 Very truly yours,

                             /s/ Timothy M. Sullivan

                                 Timothy M. Sullivan
TMS/mm