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                                                                     EXHIBIT 4.8


                          FIRST SUPPLEMENTAL INDENTURE


         FIRST SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated and
effective as of September 2, 1998, is entered into by and among Coho Energy,
Inc., a Texas corporation (the "Company"), Coho Oil & Gas, Inc., a Delaware
corporation (the "New Guarantor") and Marine Midland Bank, a New York banking
corporation, as Trustee (the "Trustee").

                  RECITALS OF THE COMPANY AND THE NEW GUARANTOR

         WHEREAS, the Company, the Subsidiary Guarantors and the Trustee have
executed and delivered an Indenture dated as October 1, 1997, among the Company,
the Subsidiary Guarantors and the Trustee (the "Original Indenture") providing
for the issuance by the Company of $150,000,000 aggregate principal amount of
the Company's 8 7/8% Senior Subordinated Notes due 2007 (the "Securities") and
pursuant to which the Subsidiary Guarantors have agreed, jointly and severally,
to unconditionally guarantee the due and punctual payment of the principal of,
premium, if any, and interest on the Securities and all other amounts due and
payable under the Original Indenture and the Securities by the Company
("Indenture Obligations");

         WHEREAS, the New Guarantor has become a Restricted Subsidiary and
pursuant to Section 1.01 of the Indenture is obligated to enter into this
Supplemental Indenture thereby guaranteeing the punctual payment of all
Indenture Obligations as provided in Article 11 of the Indenture;

         WHEREAS, pursuant to Section 9.01 of the Indenture, the Company, the
New Guarantor and the Trustee may enter into this Supplemental Indenture without
the consent of any Holder;

         WHEREAS, the execution and delivery of this Supplemental Indenture have
been duly authorized by a Board Resolution of the respective Board of Directors
of the Company and the New Guarantor; and

         WHEREAS, all conditions and requirements necessary to make this
Supplemental Indenture valid and binding upon the Company and the New Guarantor,
and enforceable against the Company and the New Guarantor in accordance with its
terms, have been performed and fulfilled;

         NOW, THEREFORE, in consideration of the above premises, each of the
parties hereto agrees, for the benefit of the others and for the equal and
proportionate benefit of the Holders of the Securities, as follows:

                                   ARTICLE ONE
                                THE NEW GUARANTEE

         Section 1.01 For value received, the New Guarantor, in accordance with
Article 11 of the Indenture, hereby unconditionally guarantees (the "New
Guarantee"), jointly and severally among itself and the Subsidiary Guarantors,
on a senior subordinated basis to the Trustee and its successors



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and assigns and the Holders, the due and punctual payment of the principal of,
premium, if any, and interest on the Securities and all other amounts due and
payable under the Indenture and the Securities by the Company, whether at
maturity, by acceleration, redemption, repurchase or otherwise as set forth in
the Indenture, including, without limitation, interest on the overdue principal
of, premium, if any, and interest on the Securities, to the extent lawful, all
in accordance with the terms of Article 11 of the Indenture and subject to the
limitations set forth in the Indenture. Each of the agreements made and
obligations assumed hereunder by the New Guarantor shall constitute, and shall
be deemed to constitute, a Guarantee under the Indenture and for all purposes of
the Indenture, and the New Guarantor shall be considered a Subsidiary Guarantor
for all purposes of the Indenture as if it was originally named therein as a
Subsidiary Guarantor.

         Section 1.02 The New Guarantee shall be automatically and
unconditionally released and discharged upon the occurrence of the events set
forth in Sections 8.01 and 11.06 of the Indenture.

                                   ARTICLE TWO
                                  MISCELLANEOUS

         Section 2.01 Except as otherwise expressly provided or unless the
context otherwise requires, all terms used herein which are defined in the
Indenture shall have the meanings assigned to them in the Indenture. Except as
supplemented hereby, the Indenture (including the Guarantees incorporated
therein) and the Securities are in all respects ratified and confirmed and all
the terms and provisions thereof shall remain in full force and effect.

         Section 2.02 This Supplemental Indenture shall be effective as of the
date above written.

         Section 2.03 The recitals contained herein shall be taken as the
statements of the Company and the New Guarantor, and the Trustee assumes no
responsibility for their correctness. The Trustee makes no representations as
to, and shall not be liable or accountable for, the validity or sufficiency of
this Supplemental Indenture.

         Section 2.04 This Supplemental Indenture shall be governed by and
construed in accordance with the laws of the jurisdiction which govern the
Indenture and its construction.

         Section 2.05 This Supplemental Indenture may be executed in any number
of counterparts each of which shall be an original, but such counterparts shall
together constitute but one and the same instrument.



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         IN WITNESS WHEREOF, the parties hereto have caused this Supplement to
be duly executed and their respective seals to be affixed hereunto and duly
attested all as of the day and year first above written.

                                            COHO ENERGY, INC.


                                            By: /s/
                                               --------------------------------
                                                  Eddie M. LeBlanc, III
                                                  Chief Financial Officer

Attest:


             /s/                    
--------------------------------------
     Anne Marie O'Gorman
          Secretary


                                            COHO OIL & GAS, INC.


                                            By: /s/  
                                               --------------------------------
                                                  Eddie M. LeBlanc, III
                                                  Chief Financial Officer
Attest:


            /s/                    
--------------------------------------
       Anne Marie O'Gorman
           Secretary


                                            MARINE MIDLAND BANK, as Trustee


                                            By:  /s/      
                                               --------------------------------
                                            James M. Foley
                                            Assistant Vice President
Attest:


By:      /s/                    
   -----------------------------------
Anthony R. Bufinsky
Corporate Trust Officer



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