Exhibit 5.1

                                TOMB AND TOMB
                              Attorneys at Law
                        402 Indiana Theatre Building
                         Indiana, Pennsylvania 15701


                                June 17, 1994



First Commonwealth Financial Corporation
Old Courthouse Square
22 North Sixth Street
Indiana, Pennsylvania  15701

Gentlemen:

          We have acted as counsel to First Commonwealth Financial Corporation
("FCFC") in connection with the Agreement and Plan of Reorganization made as of
March 25, 1994 by FCFC and United National Bancorporation ("United") and the
related Plan of Merger dated March 25, 1994 between United and FCFC
(collectively, the "Agreements").  The Agreements provide for the merger of
United into FCFC (the "Merger").  In the Merger, each issued and outstanding
share of common stock, par value $2.50 per share, of United ("United Common
Stock") (other than shares as to which the holders exercise dissenters' rights)
will be converted into 2 shares of common stock, par value $1 per share, of FCFC
("FCFC Common Stock").

          We have also acted as counsel to FCFC in connection with the
Registration Statement on Form S-4 (the "Registration Statement") to be filed by
FCFC with the Securities and Exchange Commission for the purpose of registering
under the Securities Act of 1933, as amended, the 1,637,580 shares of FCFC
Common Stock which may be issued to the shareholders of United in connection
with the Merger.  This opinion is being furnished to you for the purpose of
being filed as an Exhibit to the Registration Statement.

          In connection with this opinion, we have examined, among other things:

          (1)  An executed copy of the Agreement and Plan of Reorganization;

          (2)  A copy of the Articles of Incorporation and By-Laws of FCFC as in
               effect on the date hereof; and

 
First Commonwealth Financial Corporation                            -2-


          (3)  Copies of resolutions adopted by the Board of Directors of FCFC,
               including resolutions approving the Agreements.

          Based upon the foregoing and upon an examination of such other
documents, corporate proceedings, statutes and decisions as we have considered
necessary to enable us to furnish this opinion, and assuming that the Merger is
consummated in accordance with the terms of the Agreements, we are pleased to
advise you that in our opinion, the shares of FCFC Common Stock into which
United Common Stock outstanding immediately before the Merger becomes effective
will be converted will, at the time the Merger becomes effective, be duly
authorized, validly issued, fully paid and nonassessable shares of FCFC Common
Stock.

          We hereby consent to the filing of this opinion as an Exhibit to the
Registration Statement and to the reference to us under the caption "Legal
Opinions" in the Proxy Statement/Prospectus forming a part of the Registration
Statement.

                                    Very truly yours,

                                    Tomb and Tomb