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                                                                      EXHIBIT 23

                                  [LETTERHEAD]

                                   March 23, 2000

Permian Basin Royalty Trust
Bank of America, N.A., Trustee
901 Main Street
Dallas, Texas

Gentlemen:

     Cawley, Gillespie & Associates, Inc. hereby consents to the use of the oil
and gas reserve information in the Permian Basin Royalty Trust Securities and
Exchange Commission Form 10-K for the year ending December 31, 1999 and in the
Permian Basin Royalty Trust Annual Report for the year ending December 31, 1999,
based on reserve reports dated March 21, 2000 prepared by Cawley, Gillespie &
Associates, Inc.

                                          Submitted,

                                          /s/ CAWLEY, GILLESPIE & ASSOCIATES
                                          --------------------------------------
                                           CAWLEY, GILLESPIE & ASSOCIATES, INC.