MUTUAL NON-COMPETITION AGREEMENT

     This Mutual Non-Competition Agreement (this "Agreement") is entered into as
of the close of business December 31, 2000 (the "Effective Date"), between Prime
Medical Services, Inc., a Delaware corporation ("PMSI"), Prostatherapies,  Inc.,
a Delaware  corporation  ("Prostatherapies"),  Innovative Medical  Technologies,
Inc.,  an exempted  company  incorporated  in the Cayman  Islands  with  limited
liability ("IMT"), and Ronald Sorensen, M.D. ("Sorensen").

                             Preliminary Statements

         Concurrently  with the execution and delivery of this  Agreement,  PMSI
and IMP are  consummating  that certain Stock Purchase  Agreement (the "Purchase
Agreement"), dated effective as of the close of business December 31, 2000.

         The parties to this Agreement  (each, a "Party")  acknowledge and agree
that  this  Agreement  is  ancillary  to the  Purchase  Agreement  and all other
Transaction Documents (as defined in the Purchase Agreement).

         Each Party will receive material,  valuable benefits as a result of the
consummation of the transactions contemplated by the Transaction Documents.

         Each Party acknowledges and agrees that the other unaffiliated  Parties
would not enter into, or consent to their applicable subsidiaries and affiliates
entering into, any of the Transaction  Documents  unless such Party entered into
this Agreement.

         In  order  to  induce  each of the  other  Parties  to  consummate  the
transactions  contemplated by the Purchase  Agreement,  each Party has agreed to
certain  restrictions on the activities of it and its Affiliates (as hereinafter
defined), which restrictions each Party deems reasonable and appropriate.

                             Statement of Agreement

         NOW THEREFORE,  in  consideration  of the premises and mutual covenants
contained  herein and for other good,  valuable and binding  consideration,  the
receipt and sufficiency of which are hereby acknowledged, the Parties, intending
to be legally bound hereby, agree as follows:

         1.  Non-Competition  Agreement  of PMSI.  As a material  inducement  to
Prostatherapies,  IMT and  Sorensen  agreeing  to  enter  into  the  Transaction
Documents, PMSI hereby agrees that, until the expiration of five (5) years after
the Effective  Date,  PMSI will not directly or  indirectly,  either through any
kind of ownership  (other than ownership of securities of a publicly held entity
of which  it owns  less  than  five  percent  (5%) of any  class of  outstanding
securities),  or  as  a  principal,   shareholder,   agent,  employer,  advisor,
consultant, co-partner or in any individual or representative capacity whatever,
either for its own benefit or for the benefit of any other  person,  corporation
or other entity,  without the prior written  consent of Sorensen,  commit any of
the following acts,  which acts shall be considered  violations of this covenant
not to compete:

                  (a) Directly or indirectly,  anywhere within the United States
         of  America,  engage in or  provide,  any  services  related to (i) the
         operating  of centers or  facilities  that provide  minimally  invasive
         thermotherapy treatment of benign prostatic hyperplasia through thermal
         ablation ("Prostatherapy"),  or (ii) providing any management services,
         training  or  consulting  services  related  to any  of the  activities
         described in (i);

                  (b) Directly or indirectly provide, anywhere within the United
         States  of  America,   (i)  facilities,   equipment  and  non-physician
         personnel for the performance by physicians of Prostatherapy,  (ii) the
         marketing, scheduling and management of Prostatherapy procedures, (iii)
         the credentialing and scheduling of physicians to perform Prostatherapy
         procedures  and (iv) the billing,  collecting or accounting for the use
         of any such facilities, equipment or non-physician personnel;

                  (c) Directly or indirectly request or advise any person, firm,
         physician,  corporation or other entity having a business  relationship
         with Prostatherapies,  IMT, Sorensen,  or any affiliate,  subsidiary or
         related entity of any of the foregoing, to withdraw, curtail, or cancel
         its business with such person or entity; or

                  (d)   Directly   or   indirectly    hire   any   employee   of
         Prostatherapies, IMT, Sorensen, or any affiliate, subsidiary or related
         entity of any of the  foregoing,  or induce or attempt to influence any
         employee of  Prostatherapies,  IMT,  Sorensen,  or any such  affiliate,
         subsidiary  or related  entity to terminate  its  employment  with such
         person or entity.

         Furthermore,  to the extent  legally  permissible,  PMSI  agrees  that,
during  the  term  of  this   Agreement,   PMSI  will  (a)  refer  requests  for
Prostatherapy   procedures  only  to  Prostatherapies  for  performance  at  the
facilities  of,  and  using the  equipment  of,  Prostatherapies;  and (b) refer
inquiries from those  interested in the development of and/or  participation  in
Prostatherapy services to Prostatherapies.

         2. Non-Competition Agreement of Prostatherapies, IMT and Sorensen. As a
material  inducement to PMSI agreeing to enter into the  Transaction  Documents,
each  of  Prostatherapies,  IMT and  Sorensen  hereby  agrees  that,  until  the
expiration  of five (5) years  after the  Effective  Date,  such  Party will not
directly  or  indirectly,  either  through  any kind of  ownership  (other  than
ownership  of  securities  of a publicly  held entity of which it owns less than
five percent (5%) of any class of  outstanding  securities),  or as a principal,
shareholder,  agent,  employer,  advisor,  consultant,   co-partner  or  in  any
individual or representative  capacity  whatever,  either for its own benefit or
for the benefit of any other person,  corporation  or other entity,  without the
prior  written  consent of PMSI,  commit any of the following  acts,  which acts
shall be considered violations of this covenant not to compete:

                  (a) Directly or indirectly,  anywhere within the United States
         of  America,  engage in or  provide,  any  services  related to (i) the
         operating of centers or facilities that provide  treatments for urinary
         tract  stones  ("Lithotripsy"),   (ii)  the  manufacture,  maintenance,
         refurbishing,  repair,  sale, or leasing of any equipment related to or
         necessary  for the  operating  of centers or  facilities  that  provide
         Lithotripsy,  or (iii) providing any management  services,  training or
         consulting  services related to any of the activities  described in (i)
         or (ii);

                  (b) Directly or indirectly provide, anywhere within the United
         States  of  America,   (i)  facilities,   equipment  and  non-physician
         personnel for the  performance by physicians of  Lithotripsy,  (ii) the
         marketing,  scheduling and management of Lithotripsy procedures,  (iii)
         the credentialing  and scheduling of physicians to perform  Lithotripsy
         procedures  and (iv) the billing,  collecting or accounting for the use
         of any such facilities, equipment or non-physician personnel;

                  (c) Directly or indirectly request or advise any person, firm,
         physician,  corporation or other entity having a business  relationship
         with PMSI, or any  affiliate,  subsidiary or related entity of PMSI, to
         withdraw,  curtail,  or cancel its business with such person or entity;
         or

                  (d) Directly or  indirectly  hire any employee of PMSI, or any
         affiliate,  subsidiary or related  entity of PMSI, or induce or attempt
         to influence any employee of PMSI, or any such affiliate, subsidiary or
         related entity to terminate its employment with such person or entity.

         As partial  consideration  for the  covenants of PMSI set forth in this
Agreement,  Sorensen and/or IMT agrees to deliver to PMSI, concurrently with the
execution  and delivery of this  Agreement,  a promissory  note in the amount of
$150,000, in the form attached hereto as Exhibit A.

         3.  Agreement.  Each Party has reviewed and  carefully  considered  the
provisions  of Sections 1 and 2 of this  Agreement  and,  having done so, agrees
that the  restrictions  applicable  to it as set forth  therein (a) are fair and
reasonable with respect to time,  geographic area and scope,  (b) are not unduly
burdensome  to it, and (c) are  reasonably  required for the  protection  of the
interests of the other Parties for whose benefit such  restrictions  were agreed
upon.

         4.  Remedies.  Each Party  agrees that a  violation  on its part of any
applicable  covenant  contained in Sections 1 or 2 of this  Agreement will cause
the other  Parties,  for whose  benefit  such  restrictions  were  agreed  upon,
irreparable  damage for which remedies at law may be insufficient,  and for that
reason, it agrees that any of the other Parties shall be entitled as a matter of
right to equitable  remedies,  including  specific  performance  and  injunctive
relief,  therefor. The right to specific performance and injunctive relief shall
be cumulative and in addition to whatever other  remedies,  at law or in equity,
that the other Parties may have, including, specifically, recovery of additional
damages.

         5.  Affiliates.  For purposes of this  Agreement,  an  "Affiliate" of a
Party  means any person  married  to, or any minor  child of, such Party and any
corporation, partnership or other entity that, at the date hereof or at any time
during the term hereof,  is controlled  by, or under common  control with,  such
Party.  "Control" (and its derivatives),  in this context,  means the possession
of,  directly or  indirectly,  the power to direct or cause the direction of the
management of the  applicable  corporation,  partnership  or other entity either
through the  ownership  of voting  securities  (or other equity  interests),  by
contract,  or by ownership of a membership  of a nonstock  corporation  or other
entity  enabling a Party to elect one or more members of the governing  board of
that nonstock corporation or other entity.

     6. Control of Affiliates'  Actions.  Each Party will timely exercise all of
its rights and powers to cause each of its  Affiliates  to comply with the terms
of this Agreement.

     7.  Indemnity.  Each Party agrees to indemnify,  defend and hold each other
Party  harmless  from and  against  any and all loss,  damage,  cost and expense
(including attorneys' fees) that may result from any breach or threatened breach
of this Agreement by it or any of its Affiliates.

         8.       Miscellaneous.

     (a)  Amendments.  This  Agreement  may be  modified  or amended  only by an
instrument in writing executed by all Parties.

     (b) Headings.  The headings  contained in this  Agreement are for reference
purposes only and shall not affect in any way the meaning or  interpretation  of
this Agreement.

     (c)  Governing  Law.  This  Agreement  shall be  construed  and enforced in
accordance  with the internal laws of the State of Texas,  and not the conflicts
of law provisions thereof.

                  (d) Parties Bound. This Agreement shall be binding upon and be
         enforceable against each Party and each Party's  Affiliates,  and their
         respective  successors and representatives.  This Agreement shall inure
         to the benefit of each Party and such  Party's  respective  successors,
         representatives and assigns.

                  (e) Invalid  Provisions.  If any  provision of this  Agreement
         (including,   without   limitation,   any  provision  relating  to  the
         activities  covered by, or time period of, the  covenants  contained in
         Section  1 or  Section  2 of this  Agreement)  is  held to be  illegal,
         invalid or unenforceable  under present or future laws effective during
         the  term  hereof,  such  provision  shall  be  fully  severable;  this
         Agreement  shall be construed and enforced as if such illegal,  invalid
         or unenforceable  provision had never comprised a part hereof;  and the
         remaining  provisions  shall  remain in full force and effect and shall
         not be affected by the illegal,  invalid or unenforceable  provision or
         by its  severance  herefrom.  Furthermore,  in lieu  of  such  illegal,
         invalid or unenforceable provision,  there shall be added automatically
         as a part of this  Agreement  a  provision  as similar in terms to such
         illegal,  invalid or unenforceable  provision as may be possible and be
         legal, valid and enforceable.

                  (f)  Construction.  This Agreement shall be construed  without
         regard to the identity of the person who drafted the various provisions
         of this Agreement.  Each and every provision of this Agreement shall be
         construed  as though  all of the  Parties  participated  equally in the
         drafting of this Agreement.  Consequently,  each Party acknowledges and
         agrees that any rule of construction that a document is to be construed
         against the drafting party shall not be applicable to this Agreement.

                  (g) Other  Agreements.  Each Party  agrees  that any  material
         breach  by it of  any of  the  terms  and  provisions  of the  Purchase
         Agreement,  or any other  Transaction  Document to which it is a party,
         shall  also be  deemed  to have  been a  material  breach by it of this
         Agreement, for all purposes.

     (h) Defined  Terms.  Any  capitalized  terms not otherwise  defined in this
Agreement shall have the same meaning as set forth in the Purchase Agreement.

                            [Signature page follows]


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S-1

                                SIGNATURE PAGE TO

                        MUTUAL NON-COMPETITION AGREEMENT

         EXECUTED to be effective as of the date first above written.

PMSI:                       Prime Medical Services, Inc.

                            By:

                                 Cheryl Williams, Senior Vice President and
                                        Chief Financial Officer


Prostatherapies:            Prostatherapies, Inc.

                            By:

                                Ronald Sorensen, M.D., President

IMT:                        Innovative Medical Technologies, Inc.

                            By:

                                Ronald Sorensen, M.D., President

SORENSEN:

                                Ronald Sorensen, M.D.



<PAGE>


A-1

                                    EXHIBIT A

                             FORM OF PROMISSORY NOTE