EXHIBIT 10.91



                                 FIFTH AMENDMENT

                  FIFTH AMENDMENT, dated as of May 10, 1999 (this "Amendment"),
to the Second Amended and Restated Credit Agreement, dated as of June 6, 1997,
as amended and restated through September 14, 1998 and as amended by the First
Amendment dated as of November 19, 1998, the Second Amendment dated as of
December 29, 1998, the Third Amendment dated as of April 8, 1999 and the Fourth
Amendment dated as of April 15, 1999 (the "Credit Agreement"), among Key Energy
Group, Inc. (now known as Key Energy Services, Inc.), a Maryland corporation
(the "Borrower"), the several Lenders from time to time parties thereto, PNC
Bank, National Association ("PNC"), as Administrative Agent, Norwest Bank Texas,
N.A., as Collateral Agent and PNC Capital Markets, Inc., as Arranger.

                  The parties hereto hereby agree as follows:

                  Section 1. DEFINED TERMS. Unless otherwise defined herein,
terms which are defined in the Credit Agreement and used herein as defined terms
are so used as so defined.

                  Section 2. AMENDMENT TO SUBSECTION 2.10(d) (MANDATORY
PREPAYMENTS AND COMMITMENT REDUCTIONS--SIGNIFICANT DISPOSITION). Subsection
2.10(d) of the Credit Agreement is hereby amended by deleting such subsection in
its entirety and substituting in lieu thereof the following new Subsection
2.10(d):

                           "(d) [Intentionally left blank]."

                  Section 3. AMENDMENT TO SUBSECTION 7.5(c) (LIMITATION ON
FUNDAMENTAL CHANGES). Subsection 7.5(c) of the Credit Agreement is hereby
amended by deleting such subsection in its entirety and substituting in lieu
thereof the following new Subsection 7.5(c):

                           "(c) any Subsidiary may sell, lease, transfer or
         otherwise dispose of any or all of its assets as long as such
         transaction does not violate Section 7.6."

                  Section 4. AMENDMENT TO SUBSECTION 7.7 (LIMITATION ON
RESTRICTED PAYMENTS). Subsection 7.7 of the Credit Agreement is hereby amended
by inserting, immediately following the reference to "40%" contained in clause
(iii) of the proviso contained in such subsection, the following reference: ",
and (c) may apply up to $10,000,000 in the aggregate of the Net Cash Proceeds of
the Significant Disposition to make payments in respect of repurchases of its
Capital Stock and/or the repurchase, redemption or defeasance of Dawson 9-3/8%
Notes, Convertible Subordinated Debentures, 1997 Convertible Subordinated Notes
or Senior Subordinated Notes".

                  Section 5. AMENDMENT TO SUBSECTION 7.8 (LIMITATION ON CAPITAL
EXPENDITURES). Subsection 7.8 of the Credit Agreement is hereby amended by
inserting immediately following the phrase "except for" contained in the second
line of such subsection the following: "(a) expenditures in an amount up to
$10,000,000 in the aggregate using the Net Cash Proceeds of the Significant
Disposition and (b)".



                                                                               2

                  Section 6. AMENDMENT TO SUBSECTION 7.10 (LIMITATION ON
OPTIONAL PAYMENTS AND MODIFICATIONS OF DEBT INSTRUMENTS AND ORGANIZATIONAL
DOCUMENTATION, ETC.). Subsection 7.10 of the Credit Agreement is hereby amended
by deleting the period at the end of such subsection and inserting the following
new clause (v):

                           ", and (v) the Borrower may apply up to $10,000,000
                  in the aggregate of the Net Cash Proceeds of the Significant
                  Disposition in accordance with Section 7.7(c)."

                  Section 7. CONDITIONS TO EFFECTIVENESS OF THIS AMENDMENT. This
Amendment shall become effective as of the date (the "Effective Date") that the
Administrative Agent shall have received (a) this Amendment, executed and
delivered by a duly authorized officer of the Borrower and the Required Lenders
(and, in the case of Section 2 of this Amendment, the Required Prepayment
Lenders), (b) the attached Acknowledgment and Consent, executed and delivered by
a duly authorized officer of each of the signatories thereto, and (c) such other
corporate documents and resolutions as the Administrative Agent may request.

                  Section 8. MISCELLANEOUS.

                  (a) REPRESENTATIONS AND WARRANTIES. The Borrower represents
         and warrants to the Administrative Agent and the Lenders that as of the
         Effective Date, after giving effect to this Amendment, no Default or
         Event of Default has occurred and is continuing, and the
         representations and warranties made by the Borrower in or pursuant to
         the Credit Agreement or any Loan Documents are true and correct in all
         material respects on and as of the Effective Date as if made on such
         date (except to the extent that any such representations and warranties
         expressly relate to an earlier date, in which case such representations
         and warranties were true and correct in all material respects on and as
         of such earlier date).

                  (b) CONTINUING EFFECT OF THE CREDIT AGREEMENT. This Amendment
         shall not constitute an amendment or waiver of or consent to any
         provision of the Credit Agreement not expressly referred to herein and
         shall not be construed as an amendment, waiver or consent to any action
         on the part of the borrower that would require an amendment, waiver or
         consent to any action on the part of the Borrower that would require an
         amendment, waiver or consent of the Agents or the Lenders except as
         expressly stated herein. Except as expressly consented to hereby, the
         provisions of the Credit Agreement are and shall remain in full force
         and effect.

                  (c) FEES AND EXPENSES. The Borrower agrees to pay or reimburse
         the Administrative Agent on demand for all its reasonable out-of-pocket
         costs and expenses incurred in connection with the preparation and
         execution of this Amendment, including, without limitation, the
         reasonable fees and disbursements of counsel to the Administrative
         Agent.

                  (d) COUNTERPARTS. This Amendment may be executed in any number
         of counterparts (including by telecopy) by the parties hereto, each of
         which counterparts



                                                                               3

         when so executed shall be an original, but all counterparts taken
         together shall constitute one and the same instrument.

                  (e) GOVERNING LAW. THIS WAIVER AND AMENDMENT AND THE RIGHTS
         AND OBLIGATIONS OF THE PARTIES UNDER THIS AMENDMENT SHALL BE GOVERNED
         BY, AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE
         STATE OF NEW YORK.





                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be duly executed and delivered by their proper and duly authorized
officers as of the day and year first above written.

                                         KEY ENERGY SERVICES, INC. (formerly
                                         known as Key Energy Group, Inc.)


                                         By:/s/ Stephen E. McGregor
                                            ------------------------------------
                                         Title: Executive Vice President


                                         PNC BANK, NATIONAL ASSOCIATION,
                                         as Administrative Agent and as a Lender


                                         By:/s/ Thomas A. Majeski
                                            ------------------------------------
                                         Title: Senior Vice President


                                         NORWEST BANK TEXAS, N.A.


                                         By:/s/ Dale S. Gravelle
                                            ------------------------------------
                                         Title: Vice President


                                         BANK POLSKA KASA OPIEKI S.A.,
                                         PEKAO S.A. GROUP, NEW YORK
                                         BRANCH


                                         By:/s/ Hussein B. El-Tawil
                                            ------------------------------------
                                         Title: Vice President


                                         BANK LEUMI, USA


                                         By:/s/ Joung Hee Hong
                                            ------------------------------------
                                         Title: Vice President


                                         BOEING CAPITAL CORPORATION


                                         By:/s/ David Nelson
                                            ------------------------------------
                                         Title: Special Credits Officer


                                         THE CIT GROUP/EQUIPMENT
                                         FINANCING, INC.


                                         By: /s/ Renay Jeune
                                            ------------------------------------
                                         Title: Senior Credit Analyst

                                         KZH HIGHLAND-2 LLC


                                         By:
                                         Title:


                                         KZH PAMCO LLC


                                         By:
                                         Title:


                                         PAMCO CAYMAN LTD.

                                         By: Highland Capital Management, L.P.,
                                             as Collateral Manager


                                         By:
                                         Title:


                                         ML CLO XX PILGRIM AMERICA
                                         (CAYMAN) LTD.

                                         By: Pilgrim Investments, Inc. as its
                                             Investment Manager


                                         By:
                                         Title:


                                         PILGRIM PRIME RATE TRUST

                                         By: Pilgrim Investments, Inc., as its
                                             Investment Manager


                                         By:
                                         Title:


                                         MERRILL LYNCH PRIME RATE
                                         PORTFOLIO

                                         By: Merrill Lynch Asset Management,
                                             L.P., as Investment Advisor


                                         By:
                                         Title:


                                         MERRILL SENIOR FLOATING RATE
                                         FUND, INC.


                                         By:
                                         Title: