EXHIBIT 5.1

Opinion of Frederic Dorwart, Lawyers
Federic Dorwart, Lawyers
124 E. 4th Street
Tulsa, Okalahoma 74103


                                April 2, 2001

PetroCorp Incorporated
6733 South Yale
Tulsa, Oklahoma 74136

        Re: Registration Statement on Form S-4 (File No. 333-54544)

Ladies and Gentlemen:

        We have examined the Amendment No. 3 to the Registration Statement on
Form S-4 ("Registration Statement") to be filed by you with the Securities and
Exchange Commission in connection with the registration under the Securities Act
of 1933, as amended, of 4,108,968 shares of your common stock to be offered
pursuant to the merger agreement as described in the Registration Statement. As
your counsel in connection with these transactions, we have examined the
proceedings taken and proposed to be taken in connection with the issue in sale
of the shares.

        It is our opinion that the shares, when issued as described in the
Registration Statement, will be legally and validly issued, fully paid, and
non-assessable.

        We consent to the use of this opinion as an exhibit to the Registration
Statement, including the prospectus constituting a part thereof and any
amendment thereto.


                                        Sincerely,

                                        /s/ FREDERIC DORWART
                                        ---------------------------------
                                        Frederic Dorwart