<PAGE>
                                                                    EXHIBIT 10.1


                               AMENDMENT NO. 2 TO
                   MINI-MED/DENTAL BENEFIT EXTENSION AGREEMENT


         THIS AMENDMENT NO. 2 TO MINI-MED/DENTAL BENEFIT EXTENSION AGREEMENT
(the "Amendment") is made and entered into this 31st day of December, 2002, by
and between Atmos Energy Corporation, a Texas and Virginia corporation (the
"Company"), and CHARLES K. VAUGHAN ("Mr. Vaughan").

         WHEREAS, on May 11, 1994, the Company and Mr. Vaughan entered into that
certain Mini-Med/Dental Benefit Extension Agreement, effective October 1, 1994
(the "Agreement"); and

         WHEREAS, on August 14, 2001, the Company and Mr. Vaughan entered into
that certain Amendment No. 1 to Mini-Med/Dental Benefit Extension Agreement; and

         WHEREAS, the Company and Consultant desire to further amend the
Agreement as set forth below, to clarify that the benefits to be received during
their lifetimes by both Mr. Vaughan (and his eligible dependents) under the
Agreement shall not be subject to the annual and lifetime dollar limitations
contained in the Atmos Energy Corporation Mini-Med Plan, as restated July 1,
1995 (the "Mini-Med Plan").

         NOW THEREFORE, for and in consideration of the premises and other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereby agree as follows:

         1. Benefits Provided to Mr. Vaughan. Section 1 of the Agreement shall
be amended and restated in its entirety to read as follows:

                  From and after the Effective Date, and for the term of this
         Agreement, the Company shall pay to Mr. Vaughan, in cash (a) the
         benefits he (and his eligible dependents) would be entitled to under
         the terms of the Mini-Med Plan, as in effect from time to time during
         the term of this Agreement, if Mr. Vaughan continued to be a
         participant in the Mini-Med Plan and if he remained a participant in
         the Dental Plan, but in no event less than the benefits provided under
         the terms of the Mini-Med Plan as in effect on the Effective Date, and
         (b) the benefits Mr. Vaughan (and his eligible dependents) would be
         entitled to under the Dental Plan, as in effect from time to time
         during the term of this Agreement, if Mr. Vaughan had remained an
         employee of the Company through the term of this Agreement, but in no
         event less than the benefits provided under the terms of the Dental
         Plan as in effect on the Effective Date. The benefits to be provided to
         Mr. Vaughan (and his eligible dependents) under this Agreement shall
         not be


<PAGE>

         subject to the annual and lifetime benefit limitations on benefits set
         forth in Section 3.2 of the Mini-Med Plan.

         2. No Other Amendment. Except as expressly amended hereby, all of the
other terms, provisions, and conditions of the Agreement are hereby ratified and
confirmed and shall remain unchanged and in full force and effect. To the extent
any terms or provisions of this Amendment conflict with those of the Agreement,
the terms and provisions of the Agreement shall control. This Amendment shall be
deemed a part of, and is hereby incorporated into the Agreement. The Agreement
and any and all other documents heretofore, now, or hereafter executed and
delivered pursuant to the terms of the Agreement are hereby amended so that any
reference to the Agreement shall mean a reference to the Agreement as amended
hereby.

         3. Governing Law. This Amendment shall be governed by, and construed in
accordance with, the laws of the State of Texas.

         4. Counterparts. This Amendment may be executed in counterparts, each
of which will be an original, but all of which together will constitute one and
the same agreement.

         5. Capitalized Terms. Capitalized terms not otherwise defined herein
shall have the meanings ascribed to them in the Agreement.

         IN WITNESS WHEREOF, the parties hereto have executed this Amendment
effective as of the date and year first above written.



                                      ATMOS ENERGY CORPORATION


                                      By: /s/ ROBERT W. BEST
                                          -------------------------------
                                             Robert W. Best
                                             Chairman, President and
                                             Chief Executive Officer



                                          /s/ CHARLES K. VAUGHAN
                                          -------------------------------
                                             CHARLES K. VAUGHAN