Exhibit 5

                               October 16, 1997


Magnum Hunter Resources, Inc.
600 East Las Colinas Blvd.
Suite 1200
Irving, Texas  75039



Dear Sirs:

         We have acted as counsel for Magnum  Hunter  Resources,  Inc., a Nevada
corporation  (the  "Company"),  in  connection  with the  Company's  offer  (the
"Exchange  Offer") to exchange  its 10% Senior  Notes due 2007 to be  registered
under the Securities  Act of 1933 (the "Exchange  Notes") for any and all of its
outstanding 10% Senior Notes due 2007 (the "Outstanding Notes"). The Outstanding
Notes are, and the Exchange Notes will be, fully and unconditionally  guaranteed
(the  "Subsidiary  Guarantees,"  and  together  with  the  Exchange  Notes,  the
"Securities")  on a joint and several basis by Magnum Hunter  Production,  Inc.,
Gruy Petroleum  Management  Company,  Rampart Petroleum,  Inc. and ConMag Energy
Corporation (collectively, the "Initial Subsidiary Guarantors"). The Outstanding
Notes have been, and the Exchange Notes will be, issued pursuant to an Indenture
dated as of May 29,  1997 (the  "Indenture"),  among the  Company,  the  Initial
Subsidiary  Guarantors  and First  Union  National  Bank of North  Carolina,  as
trustee.

         In  connection  with  such  matters,  we have  examined  the  Indenture
(including  the  Subsidiary  Guarantees  contained  therein),  the  Registration
Statement on Form S-4 filed by the Company and the Initial Subsidiary Guarantors
with  the  Securities  and  Exchange  Commission  for  the  registration  of the
Securities  under the Securities  Act of 1933 (the  Registration  Statement,  as
amended at the time it becomes effective, being referred to as the "Registration
Statement")  and such corporate  records of the Company,  certificates of public
officials and such other  documents as we have deemed  necessary or  appropriate
for the purpose of this opinion.

         Based upon the foregoing, subject to the qualifications hereinafter set
forth, and having regard for such legal  considerations as we deem relevant,  we
are of the opinion  that the  Securities  proposed to be issued  pursuant to the
Exchange  Offer  have been duly  authorized  for  issuance  and,  subject to the
Registration  Statement becoming effective under the Securities Act of 1933, and
to  compliance  with any  applicable  state  securities  laws,  when  issued and
delivered in  accordance  with the  Exchange  Offer and the  Indenture,  (i) the
Exchange  Notes will  constitute  valid and legally  binding  obligations of the
Company, entitled to the benefits of the Indenture and the Subsidiary Guarantees
contained therein, and (ii) the Subsidiary  Guarantees will constitute valid and
legally binding obligations of the Initial Subsidiary Guarantors.



<PAGE>


Magnum Hunter Resources, Inc.
October 16, 1997
Page 2


         The opinions  expressed  above are limited by,  subject to and based on
the assumptions, limitations and qualifications set forth below:

                  (a) The validity and binding  effect of the Exchange Notes and
         the  Subsidiary  Guarantees  may be limited or affected by  bankruptcy,
         reorganization,  insolvency, fraudulent conveyance, moratorium or other
         similar laws relating to or affecting  creditors'  rights generally and
         by general  equitable  principles  (regardless of whether such validity
         and binding effect are considered in a proceeding in equity or at law),
         and except as rights to indemnity and contribution  under the Indenture
         (including the Subsidiary  Guarantees contained therein) may be limited
         by applicable laws or policies underlying such laws.

                  (b) We are members of the bar of the State of Texas and do not
         hold  ourselves  out  as  being   conversant   with  the  laws  of  any
         jurisdiction  other  than  those of the State of Texas  and the  United
         States of America, and we express no opinion herein with respect to the
         laws of any such other jurisdiction.  Insofar as the opinions expressed
         herein  relate to matters  governed by New York law,  we have  assumed,
         without knowing and without making any investigation to determine, that
         such laws are the same as the laws of the State of Texas.

         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
Matters" in the  Prospectus  forming a part of the  Registration  Statement.  In
giving this consent,  we do not thereby admit that we are within the category of
persons whose consent is required  under Section 7 of the Securities Act of 1933
and  the  rules  and  regulations  of the  Securities  and  Exchange  Commission
thereunder.


                                            Respectfully submitted,

                                            THOMPSON & KNIGHT
                                            A Professional Corporation


                                             By:/s/ David E. Morrison
                                                ---------------------------
                                                David E. Morrison, Attorney