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                                                                    EXHIBIT 4.12


                          AMENDMENT TO RIGHTS AGREEMENT

         AMENDMENT TO RIGHTS AGREEMENT (this "Amendment") dated as of the 27 day
of August, 2002, between Harken Energy Corporation, a Delaware corporation (the
"Company"), and American Stock Transfer and Trust Company (successor to Mellon
Investor Services LLC, a New Jersey limited liability company (formerly known as
ChaseMellon Shareholder Services L.L.C.)), as Rights Agent (the "Rights Agent").

                                    RECITALS

         1. The Company and the Rights Agent have previously entered into that
certain Rights Agreement, dated as of April 6, 1998 (the "Agreement").

         2. Section 27 (Supplements and Amendments) of the Agreement provides,
in part, that, as long as the Rights are redeemable, the Agreement may be
supplemented or amended without the approval of any holders of Rights.

         3. The Company may distribute to it stockholders and certain other
parties, non-transferable rights to subscribe for and purchase the Company's
Common Stock, $0.01 par value ("Common Stock") pursuant to an offering of such
rights which is authorized and approved by the Company's Board of Directors
prior to December 31, 2002.

         4. The Company desires to amend the Agreement to ensure that no Person
will be deemed to be an Acquiring Person (as defined in the Agreement) solely as
a result of acquiring the Company's Common Stock upon the exercise of such
rights in such rights offering under the circumstances described herein.

                                    AGREEMENT

         Section 1.  Definitions.  All capitalized terms used but not defined
herein shall have the meanings given to them in the Agreement.

         Section 2.  Amended Definition. Pursuant to Section 27 of the Agreement
(Supplements and Amendments), the undersigned wish to amend Section 1(k) of the
Agreement (Certain Definitions -- Exempt Person) by deleting the existing
Section 1(k) in its entirety and replacing it with a new Section 1(k) to read as
follows:

         "(k) "Exempt Person" shall mean (i) the Company or any Subsidiary (as
         such term is hereinafter defined) of the Company, in each case
         including, without limitation, in its fiduciary capacity, or any
         employee benefit plan of the Company or any Subsidiary of the Company,
         or any entity or trustee holding Common Stock for or pursuant to the
         terms of any such plan or for the purpose of funding any such plan or
         funding other employee benefits for employees of the Company or of any
         Subsidiary of the Company, (ii) any Person who or which is or becomes
         the Beneficial Owner of 15% or more of the shares of Common Stock then
         outstanding as the result of such Person's Beneficial Ownership of

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         the Company's 5% Convertible Subordinated Notes due 2003, or
         acquisition from the Company of the Company's securities, and any
         shares of Common Stock issued by the Company to such Person upon
         conversion, exchange or redemption thereof, in exchange for the
         Company's 5% Convertible Subordinated Notes due 2003 held by such
         Person or both, unless and until such Person, while a Beneficial Owner
         of 15% or more of the shares of Common Stock then outstanding, shall
         become the Beneficial Owner of additional shares of Common Stock
         constituting 1% or more of the then outstanding shares of Common Stock
         other than pursuant to such exchange, conversion or redemption, and
         (iii) any Person who or which is or becomes the Beneficial Owner of 15%
         or more of the shares of Common Stock then outstanding as the result of
         such Person's acquisition from the Company of rights to subscribe for
         and purchase Common Stock pursuant to an offering of such rights
         authorized and approved by the Board of Directors of the Company prior
         to December 31, 2002 (the "Board Approved Rights Offering"), and any
         shares of Common Stock issued by the Company to such Person upon
         exercise of such rights, unless and until such Person, while a
         Beneficial Owner of 15% or more of the shares of Common Stock then
         outstanding, shall become a Beneficial Owner of additional shares of
         Common Stock constituting 1% or more of the then outstanding shares of
         Common Stock other than pursuant to such Board Approved Rights
         Offering.

         Section 3. Governing Law. This Amendment shall be deemed to be a
contract made under the laws of the State of Delaware and for all purposes shall
be governed by and construed in accordance with the laws of such State
applicable to contracts made and to be performed entirely within such State.

         Section 4. Counterparts.  This Agreement may be executed in any number
of counterparts and each of such counterparts shall for all purposes be deemed
to be an original, and all such counterparts shall together constitute but one
and the same instrument.

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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
Rights Agreement to be duly executed as of the day and year first above written.

                                      HARKEN ENERGY CORPORATION


                                      By: /s/ Bruce N. Huff
                                          --------------------------------------
                                          Bruce N. Huff
                                          President and Chief Operating Officer

                                      AMERICAN STOCK TRANSFER AND TRUST
                                      COMPANY, as Rights Agent


                                      By: /s/___________________________________
                                          Name:_________________________________
                                          Title:________________________________

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