1 CONSENT OF CAWLEY, GILLESPIE & ASSOCIATES INC. EXHIBIT 23 [LETTERHEAD] March 21, 2001 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, 2000 and in the Permian Basin Royalty Trust Annual Report for the year ending December 31, 2000, based on reserve reports dated March 20, 2001 prepared by Cawley, Gillespie & Associates, Inc. Submitted, /s/ CAWLEY, GILLESPIE & ASSOCIATES -------------------------------------------- CAWLEY, GILLESPIE & ASSOCIATES, INC.