EXHIBIT 5






                                 JENKENS & GILCHRIST 
                             1445 Ross Avenue Suite 3200
                                 Dallas, Texas 75202

                                     May 9, 1995



          Cairn Energy USA, Inc.
          8235 Douglas Avenue, Suite 1221
          Dallas, Texas 75225

               Re:  Offering by  Cairn Energy  PLC of Common  Stock of
                    Cairn Energy USA, Inc. on Form S-3

          Gentlemen:

               On  May  9,  1995,  Cairn  Energy   USA,  Inc.,  a  Delaware
          corporation (the  "Company"), will  file with the  Securities and
          Exchange Commission  a  Registration Statement  on Form S-3  (the
          "Registration Statement")  under the  Securities Act of  1933, as
          amended (the "Act").  Such  Registration Statement relates to the
          sale by Cairn Energy PLC,  the selling stockholder (the  "Selling
          Stockholder") of an aggregate  of 2,623,260 shares (the "Shares")
          of  the Company's  common stock,  par value  $.01 per  share (the
          "Common Stock").   We  have acted  as counsel  to the  Company in
          connection with  the preparation  and filing of  the Registration
          Statement.

               In connection  therewith, we  have examined and  relied upon
          the original or copies, certified to our satisfaction, of (i) the
          Certificate  of Incorporation and  the Bylaws of  the Company, as

          amended,  (ii) copies of documents related to the merger of Cairn
          Energy USA, Inc. with and into Omni Exploration, Inc. pursuant to
          which  the  Shares  were   issued  to  the  Selling  Stockholder,
          (iii) copies of documents relating to the  issuance of the Shares
          to  the Selling  Stockholder; (iv) copies  of resolutions  of the
          Board of Directors of the Company authorizing the preparation and
          filing  of  the  Registration  Statement,  (v)  the  Registration
          Statement,  and  all  exhibits   thereto,  and  (vi)  such  other
          documents  and instruments as  we have  deemed necessary  for the
          expression  of  the opinions  herein  contained.   In  making the
          foregoing examinations,  we have  assumed the genuineness  of all
          signatures and the authenticity of  all documents submitted to us
          as originals, and  the conformity  to original  documents of  all
          documents submitted to us as certified or photostatic copies.  As
          to  various questions of fact  material to this  opinion, we have
          relied,  to  the  extent  we deem  reasonably  appropriate,  upon
          representations or  certificates of officers or  directors of the
          Company and upon documents,  records and instruments furnished to
          us by  the Company, without independent check  or verification of
          their accuracy.

               Based upon the foregoing examination, we  are of the opinion
          that the  Shares to  be sold by  the Selling  Stockholder in  the
          offering, as  described in the Registration  Statement, have been
          duly and validly  authorized for issuance and are validly issued,
          fully paid and nonassessable.

               We  hereby consent  to  the filing  of  this opinion  as  an
          exhibit  to the Registration Statement and to the use of our name
          under the caption "Legal Matters"  in the Prospectus forming part
          of the Registration Statement.  In giving such consent, we do not
          admit that we come  within the category of persons  whose consent
          is required by Section 7 of the Act or the  rules and regulations
          of the Commission thereunder.

                                        Very truly yours,

                                        JENKENS & GILCHRIST,
                                          a Professional Corporation



                                        By:  Mark D. Wigder
                                             Mark D. Wigder
                                             Authorized Signatory

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