EXHIBIT 5







                                            December 7, 1994



Board of Directors
First Financial Corporation
1305 Main Street
Stevens Point, Wisconsin 54481

Gentlemen:

                  I am the General  Counsel  and  Secretary  of First  Financial
Corporation,  a Wisconsin  corporation (the  "Company").  This opinion letter is
given in connection with the Company's  registration  statement on Form S-4 (the
"Registration Statement"),  as filed with the Securities and Exchange Commission
on the date hereof and  relating  to the  proposed  offering of up to  5,500,000
shares of the Company's  common stock,  par value $1.00 per share,  all of which
shares (the "Shares") may be issued in connection with the proposed  acquisition
of FirstRock Bancorp,  Inc.  ("FirstRock")  pursuant to an Agreement and Plan of
Reorganization  dated as of October 26,  1994,  as amended,  among the  Company,
FirstRock  and First  Financial  Acquisition  Company  (the  "Agreement").  This
opinion  letter is furnished to you at your request to enable you to fulfill the
requirements of Item 60(b)(5) of Regulation S-K, 17 C.F.R. ss. 229.601(b)(5), in
connection with the Registration Statement.

                  For purposes of this opinion letter, I have examined copies of
the following documents:

                  1.       An executed copy of the Registration Statement.

                  2.       The Certificate of Incorporation of the Company.

                  3.       The Bylaws of the Company.

                  4.       The Agreement.

                  5.       Resolutions  of the Board of Directors of the Company
                           adopted on October 19, 1994  relating to the issuance
                           of  the  Shares  and  arrangements   in    connection
                           therewith.

                  This opinion letter is given,  and all  statements  herein are
made, in the context of the foregoing.


Board of Directors
First Financial Corporation
December 7, 1994
Page 2


                  This  opinion  letter is based as to  matters of law solely on
the Business  Corporation  Law of the State of  Wisconsin.  I express no opinion
herein as to any other laws, statutes, regulations, or ordinances.

                  Based upon,  subject to and limited by the foregoing,  I am of
the opinion that following (i) effectiveness of the Registration Statement, (ii)
issuance of the Shares  pursuant to the terms of the Agreement and (iii) receipt
by the Company of the  consideration for the Shares specified in the resolutions
of the Board of Directors, the Shares will be validly issued, fully paid and non
assessable under the Business Corporation Law of the State of Wisconsin,  except
as may be found under Section  180.0622(2)(b) of Business Corporation Law of the
State of Wisconsin.

                  I assume no  obligation  to advise  you of any  changes in the
foregoing subsequent to the delivery of this opinion letter.

                  I hereby  consent  to the  filing  of this  opinion  letter as
Exhibit  5 to the  Registration  Statement  and to  the  reference  to me in the
prospectus  constituting a part of the  Registration  Statement.  In giving this
consent,  I do not thereby admit that I am an "expert" within the meaning of the
Securities Act of 1933, as amended.

                                                   Very truly yours,

                                                   /s/Robert M. Salinger

                                                   Robert M. Salinger
                                                   General Counsel and Secretary