UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    FORM 8-K
                                 CURRENT REPORT

                         Pursuant to Section 13 or 15(d)
                     of the Securities Exchange Act of 1934


          Date of Report (Date of earliest event reported): May 1, 2006



                        PIONEER NATURAL RESOURCES COMPANY
             ------------------------------------------------------
             (Exact name of registrant as specified in its charter)


           Delaware                      1-13245                75-2702753
- ------------------------------        ------------        ---------------------
       (State or other                (Commission            (I.R.S. Employer
jurisdiction of incorporation)        File Number)        Identification Number)


        5205 N. O'Connor Blvd                                     75039
              Suite 900                                        ----------
            Irving, Texas                                      (Zip code)
        ---------------------
        (Address of principal
         executive offices)


       Registrant's telephone number, including area code: (972) 444-9001

                                 Not applicable
          -------------------------------------------------------------
          (Former name or former address, if changed since last report)

Check  the  appropriate  box  below  if the  Form  8-K  filing  is  intended  to
simultaneously  satisfy the filing obligation of the Registrant under any of the
following provisions:

[ ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR
    230.425)
[ ] Soliciting material  pursuant to Rule  14a-12 under the Exchange Act (17 CFR
    240.14a-12)
[ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange
    Act (17 CFR 240.14d-2(b))
[ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange
    Act (17 CFR 240.13e-4(c))







Item 1.01. Entry into a Material Definitive Agreement

On May 1, 2006,  Pioneer Natural  Resources  Company (the "Company")  executed a
sixth supplemental indenture (the "Sixth Supplemental  Indenture") with The Bank
of New York Trust Company,  N.A., as successor trustee (the "Trustee") under the
Indenture,  dated as of January  13,  1998 (as  amended  and  supplemented,  the
"Indenture"), between the Company and the Trustee.

The Sixth  Supplemental  Indenture is attached as Exhibit 4.1, and the terms and
conditions thereof are incorporated herein by reference.

The Form of the Company's  6.875%  Senior Notes due 2018 issued  pursuant to the
Sixth  Supplemental  Indenture  is  attached as Exhibit  4.2,  and the terms and
conditions thereof are incorporated herein by reference.


Item 9.01. Financial Statements and Exhibits

      (d)  Exhibits

           4.1 -  Sixth Supplemental Indenture,  dated as of  May 1, 2006, among
                  the Company, Pioneer Natural Resources USA, Inc. and  The Bank
                  of New York Trust Company,  N.A., as Trustee,  with respect to
                  that  indenture,  dated  as of  January 13,  1998, between the
                  Company and the Trustee.

           4.2 -  Form of 6.875% Senior Notes due 2018 of the Company.






                                   SIGNATURES

     Pursuant to the  requirements  of the Securities  Exchange Act of 1934, the
registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned hereunto duly authorized.



                                    PIONEER NATURAL RESOURCES COMPANY



                                      /s/ Darin G. Holderness
                                    -------------------------------------------
                                    Darin G. Holderness
                                    Vice President and Chief Accounting Officer
Dated: May 4, 2006













                                  EXHIBIT INDEX



       Exhibit
       Number                        Exhibit Title
       -------                       -------------

         4.1 -  Sixth Supplemental Indenture, dated as of May 1, 2006, among the
                Company, Pioneer Natural Resources USA, Inc. and The Bank of New
                York Trust  Company,  N.A., as  Trustee,  with  respect  to that
                indenture, dated as of January 13, 1998, between the Company and
                the Trustee.

         4.2 -  Form of 6.875% Senior Notes due 2018 of the Company.