------------------------------ OMB APPROVAL ------------------------------ OMB Number 3235-0287 Expires: December 31, 2001 Estimated average burden hours per response ....... 0.5 ------------------------------ U.S. SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 4 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(f) of the Investment Company Act of 1940 [ ] Check this box if no longer subject of Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). (Print or Type Reponses) ================================================================================ 1. Name and Address of Reporting Person* Hummel Brad A. -------------------------------------------------------------------------------- (Last) (First) (Middle) 1301 Capital of Texas Hiway, Suite C-300 -------------------------------------------------------------------------------- (Street) Austin Texas 78746 -------------------------------------------------------------------------------- (City) (State) (Zip) ================================================================================ 2. Issuer Name and Ticker or Trading Symbol Prime Medical Services, Inc. (PMSI) ================================================================================ 3. IRS or Social Security Number of Reporting Person (Voluntary) ================================================================================ 4. Statement for Month/Year March, 2002 ================================================================================ 5. If Amendment, Date of Original (Month/Year) ================================================================================ 6. Relationship of Reporting Person to Issuer (Check all applicable) [ X] Director [ ] 10% Owner [ X] Officer (give title below) [ ] Other (specify below) Chief Executive Officer ================================================================================ 7. Individual or Joint/Group Filing (Check applicable line) [ X] Form filed by one Reporting Person [ ] Form filed by more than one Reporting Person ================================================================================ Table I -- Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned ================================================================================

* If the Form is filed by more than one Reporting Person, see Instruction 4(b)(v). Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. Page 1 of 2 FORM 4 (continued) Table II -- Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities) ================================================================================

Explanation of Responses: /s/:Brad A. Hummel 03/19/02 --------------------------------------------- ----------------------- **Signature of Reporting Person Date ** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). Note: File three copies of this Form, one of which must be manually signed. If space provided is insufficient, see Instruction 6 for procedures. Alternatively, this Form is permitted to be submitted to the Commission in electronic format at the option of the reporting person pursuant to rule 101(b)(4) of Regulation S-T. Page 2 of 2 (122797DTI)

PRIME MEDICAL SERVICES INC /TX/ 4