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


                                    FORM 11-K

              / x / ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                   For the fiscal year ended December 31, 2004

                                       OR

             / / TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

              For the transition period from _________ to _________

                        Commission File Number: 333-39249

       A. Full title of the plan and the address of the plan, if different
                      from that of the issuer named below:

          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN


      B. Name of issuer of the securities held pursuant to the plan and the
                   address of its principal executive office:

                        Pioneer Natural Resources Company
                      5205 North O'Connor Blvd., Suite 900
                               Irving, Texas 75039







          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN


                 Financial Statements and Supplemental Schedule

    As of December 31, 2004 and 2003 and for the year ended December 31, 2004

          With Report of Independent Registered Public Accounting Firm







                                       2








          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN




                                Table of Contents


                                                                          Page


Report of Independent Registered Public Accounting Firm ...............     4

Statements of Net Assets Available for Benefits as of
   December 31, 2004 and 2003..........................................     5

Statement of Changes in Net Assets Available for Benefits
   for the year ended December 31, 2004................................     6

Notes to Financial Statements..........................................     7

Schedule H; Line 4i - Schedule of Assets (Held At End of Year)
   as of December 31, 2004.............................................    13

Signatures.............................................................    14

Index to Exhibits......................................................    15




                                       3














                     REPORT OF INDEPENDENT REGISTERED PUBLIC
                                 ACCOUNTING FIRM


To the Participants and the Plan Administrator of
Pioneer Natural Resources USA, Inc. 401(k) and Matching Plan:


     We have audited the  accompanying  statements  of net assets  available for
benefits of Pioneer  Natural  Resources USA, Inc. 401(k) and Matching Plan as of
December 31, 2004 and 2003,  and the related  statement of changes in net assets
available  for benefits for the year ended  December 31, 2004.  These  financial
statements are the responsibility of the Plan's  management.  Our responsibility
is to express an opinion on these financial statements based on our audits.

     We  conducted  our audits in  accordance  with the  standards of the Public
Company Accounting Oversight Board (United States). Those standards require that
we plan and perform the audit to obtain  reasonable  assurance about whether the
financial statements are free of material  misstatement.  We were not engaged to
perform an audit of the Plan's internal  control over financial  reporting.  Our
audits included  consideration of internal control over financial reporting as a
basis for designing audit procedures that are appropriate in the  circumstances,
but not for the purpose of  expressing  an opinion on the  effectiveness  of the
Plan's internal  control over financial  reporting.  Accordingly,  we express no
such  opinion.  An audit also  includes  examining,  on a test  basis,  evidence
supporting the amounts and  disclosures in the financial  statements,  assessing
the accounting  principles used and significant estimates made by management and
evaluating the overall  financial  statement  presentation.  We believe that our
audits provide a reasonable basis for our opinion.

     In our opinion,  the financial statements referred to above present fairly,
in all material  respects,  the net assets available for benefits of the Plan at
December  31,  2004 and 2003,  and the changes in its net assets  available  for
benefits for the year ended December 31, 2004, in conformity with U.S. generally
accepted accounting principles.

     Our  audits  were  performed  for the  purpose of forming an opinion on the
financial statements taken as a whole. The accompanying supplemental schedule of
assets  (held at end of year)  as of  December  31,  2004, is presented  for the
purpose  of  additional  analysis  and is not a required  part of the  financial
statements  but is  supplementary  information  required  by the  Department  of
Labor's Rules and  Regulations  for Reporting and Disclosure  under the Employee
Retirement  Income  Security  Act of 1974.  This  supplemental  schedule  is the
responsibility  of the Plan's  management.  The  supplemental  schedule has been
subjected  to the  auditing  procedures  applied in our audits of the  financial
statements  and, in our opinion,  is fairly  stated in all material  respects in
relation to the financial statements taken as a whole.



                                                               Ernst & Young LLP




Dallas, Texas
May 17, 2005




                                       4










          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN


                 Statements of Net Assets Available for Benefits





                                                                   December 31,
                                                          -----------------------------
                                                               2004            2003
                                                          ------------    -------------

                                                                    
Investments at fair value:
  Vanguard PRIMECAP Fund..............................    $ 33,937,417    $ 27,137,082
  Vanguard Windsor II Fund............................      18,051,885      12,748,739
  Vanguard 500 Index Fund.............................      17,473,864      15,278,207
  Vanguard Prime Money Market Fund....................       9,872,070      12,564,723
  Vanguard Short-Term Investment-Grade Fund...........       6,154,323       4,976,563
  Vanguard Retirement Savings Trust...................       4,745,263       2,598,710
  Vanguard Explorer Fund..............................       4,664,506       3,325,419
  Vanguard International Growth Fund..................       3,743,138       2,081,153
  Vanguard Total Bond Market Index Fund...............       3,694,790       2,853,005
  Vanguard Asset Allocation Fund......................       3,537,314       2,244,572
  Vanguard Inflation-Protected Securities Fund........       2,693,544         942,171
  Sarofim Equity Fund.................................      12,558,831      14,842,386
  Pioneer Stock Fund .................................       5,652,423       4,964,217
                                                           -----------     -----------
                                                           126,779,368     106,556,947

Participants loans receivable.........................       2,420,298       2,150,262
                                                           -----------     -----------
                                                           129,199,666     108,707,209
Contributions receivable..............................           9,789          25,328
Unallocated accrued administrative expenses...........         (12,620)            -  
                                                           -----------     -----------
  Net assets available for benefits...................    $129,196,835    $108,732,537
                                                           ===========     ===========







                 See accompanying notes to financial statements.



                                       5








          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN


            Statement of Changes in Net Assets Available for Benefits
                      For the Year Ended December 31, 2004





                                                               
Additions to net assets available for benefits:
  Interest and dividend income................................    $  1,859,619
  Employer contributions......................................       6,039,928
  Participants contributions..................................       5,034,827
  Net appreciation in fair value of investments...............      10,864,519
  Rollovers...................................................         391,772
                                                                   -----------
                                                                    24,190,665
Deductions from net assets available for benefits:
  Distributions to participants...............................       3,695,734
  Administrative expenses.....................................          30,633
                                                                   -----------
                                                                     3,726,367

Net increase in net assets available for benefits.............      20,464,298

Net assets available for benefits, beginning of year..........     108,732,537
                                                                   -----------

Net assets available for benefits, end of year................    $129,196,835
                                                                   ===========









                 See accompanying notes to financial statements.




                                       6







          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                          NOTES TO FINANCIAL STATEMENTS
                           December 31, 2004 and 2003


Note 1.     Description of Plan

     The following description of the Pioneer Natural Resources USA, Inc. 401(k)
and Matching Plan (the "Plan") provides only general  information.  Participants
should refer to the Summary Plan  Description for a complete  description of the
Plan, a copy of which is available to each  participant from the Pioneer Natural
Resources   USA,   Inc.   401(k)  and  Matching   Plan   Committee   (the  "Plan
Administrator").  The  Plan  is  subject  to  the  provisions  of  the  Employee
Retirement Income Security Act of 1974, as amended ("ERISA").

     General

     The Plan is a defined  contribution  plan  established  on  January 1, 1990
under Section 401 of the Internal Revenue Code of 1986, as amended (the "Code").
The Plan was  established  for the benefit of the  employees of Pioneer  Natural
Resources  USA,  Inc. (the  "Employer"),  a  wholly-owned  subsidiary of Pioneer
Natural Resources  Company (the "Company").  All regular full-time and part-time
employees of the Employer are eligible to  participate  in the Plan on the first
day of the month  following  their date of hire. The Plan's assets are held in a
trust and certain  administrative  functions are performed by Vanguard Fiduciary
Trust Company, the trustee of the trust (the "Trustee").

     On  September  28,  2004,  the Company  completed  a merger with  Evergreen
Resources,  Inc.  ("Evergreen").  The Plan was amended to allow all employees of
Evergreen  who  joined  the  Company,  to  participate  in the Plan,  as well as
maintain their years of credited service.

     Contributions

     Participants may elect to contribute to the Plan an amount of not less than
two percent nor more than 30 percent of their  pre-tax  annual salary and bonus.
Additionally,  participants  may elect to make  after-tax  contributions  to the
Plan. A participant's  combined pre-tax and after-tax  contributions to the Plan
(the "Participant Contributions") may not exceed 50 percent of the participant's
annual salary and bonus. Matching  contributions are made in cash to the Plan at
an amount  equal to 200  percent  of the first five  percent  of pre-tax  annual
salary contributed by a participant to the Plan (the "Matching Contributions").

     Participants Accounts

     Participant's accounts are credited with the Participant Contributions, the
Matching  Contributions  and an allocation  of Plan earnings and  administrative
expenses.  Plan  earnings  and  administrative  expenses  are  allocated to each
participant's  accounts by fund in proportion to their fund balance  relative to
the total fund balance.

     Participants  may borrow  from  their  accounts a minimum of $1,000 up to a
maximum of $50,000 or 50 percent of their accounts' vested  balances,  whichever
amount is less.  The loans  are  secured  by the  balance  in the  participant's
accounts.  Participants loans bear interest at an annual rate equal to the prime
borrowing rate at the inception of the loan plus one percent. Loan principal and
interest is paid ratably through payroll deductions.

     Investment Options

     During the Plan year ended  December  31, 2004,  participants  were able to
allocate their contributions among the following  registered  investment company
funds, common/collective trusts and Pioneer Stock Fund:


                                       7







          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                          NOTES TO FINANCIAL STATEMENTS
                           December 31, 2004 and 2003


Note 1.     Description of Plan (continued)

     Registered Investment Company Funds:

o    Vanguard PRIMECAP Fund - Invests in stocks of companies with  above-average
     prospects for continued  earnings  growth,  strong  industry  positions and
     skilled management teams.

o    Vanguard   Windsor   II  Fund  -  Invests   in  a   diversified   group  of
     large-capitalization  companies  whose stocks are  considered by the fund's
     advisors to be undervalued or  out-of-favor.  The stocks  generally sell at
     prices  considered by the fund's  advisors to be below their overall market
     average compared to their dividend income and future return potential.

o    Vanguard 500 Index Fund - Invests in all of the 500 stocks that make up the
     Standard & Poor's 500  Composite  Stock Price  Index,  a widely  recognized
     benchmark of United States stock market performance.

o    Vanguard  Prime  Money  Market Fund - Invests in  high-quality,  short-term
     money market  instruments issued by financial  institutions,  non-financial
     corporations,  the  United  States  government  and United  States  federal
     agencies.

o    Vanguard  Short-Term  Investment-Grade  Fund - Invests in short-term bonds,
     including investment-grade corporate and United States Treasury securities.

o    Vanguard  Explorer Fund - Invests in a diversified  group of  small-company
     stocks with prospects for above-average growth.

o    Vanguard  International  Growth  Fund  -  Invests  in  stocks  of  seasoned
     companies  located  outside  the United  States with  above-average  growth
     potential.

o    Vanguard  Total  Bond  Market  Index  Fund - Invests  in a large  sample of
     securities that match key  characteristics of the Lehman Brothers Aggregate
     Bond Index.

o    Vanguard Asset Allocation Fund - Invests in common stocks, long-term United
     States Treasury bonds and money market instruments.

o    Vanguard Inflation-Protected Securities Fund - Invests in inflation-indexed
     bonds   issued  by  the  United   States   government,   its  agencies  and
     instrumentalities, and corporations.

     Common/Collective Trusts:

o    Vanguard  Retirement  Savings Trust - Invests in high-quality  fixed-income
     securities with financial backing from insurance companies and banks.

o    Sarofim   Equity  Fund  -  Invests  in  a   diversified   group  of  large,
     high-quality,  multinational  companies with favorable growth prospects and
     high incremental returns on investment.

     Pioneer  Stock  Fund - The  Pioneer  Stock  Fund  is  designed  to  provide
     long-term  growth of capital  through  increases in the value of the common
     stock of the Company. Dividends are reinvested to purchase more shares.


                                       8








          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                          NOTES TO FINANCIAL STATEMENTS
                           December 31, 2004 and 2003


Note 1.     Description of Plan (continued)

     See  Note 3 for  additional  information  regarding  investment  risks  and
uncertainties.

     Vesting

     Participants are immediately vested in their Participant Contributions made
into the Plan, plus the actual Plan earnings  thereon.  Participants vest in the
Matching Contributions,  plus the actual Plan earnings thereon,  proportionately
for each full year of completed service over a four-year period that begins with
the participant's date of hire.  Participant's account balances that were merged
into the Plan from predecessor plans retain the vesting  schedules  provided for
in the predecessor plans' documents.

     Payments of Benefits

     Vested  balances > $5,000.  If the total value of the vested portion of the
participant's  account exceeds $5,000,  payments will begin at age 70-1/2 unless
the participant terminates,  retires or becomes disabled prior to age 70-1/2 and
consents to an earlier distribution date by filing a written request to the Plan
Administrator.  Distributions  to terminated,  retired or disabled  participants
will be annuities,  but may be installments or lump-sum  payments if so directed
by the participant.

     Vested  balances < $5,000.  If the total value of the vested portion of the
participant's  accounts is $5,000 or less,  payment will be made in one lump sum
as soon as administratively possible.

     In either case,  vested amounts that are invested in the Pioneer Stock Fund
may,  at the  election of the  participant,  be  distributed  in the form of the
Company's  common stock with cash  distributed  in lieu of fractional  shares of
stock.   Under  the  Plan,  a   participant's   beneficiary   will  receive  the
participant's account balances in the event of a participant's death.

     Withdrawal of Benefits

     Current  employees  of the  Employer  may  withdraw (i) all or a portion of
their account  balances  derived from after- tax  Participant  Contributions  or
rollover  contributions;  (ii) their  vested  assets in the Plan  under  certain
hardship  conditions  as  defined  in  the  Plan  agreement;  or  (iii),  if the
participant  has attained the age of 59-1/2,  all or a portion of their  account
balances  derived from  Participant  Contributions  and Plan  earnings  thereon.
Terminated participants may withdraw their vested assets in the Plan.

     Forfeitures 

     Upon  termination of employment,  the unvested  portion of a  participant's
Matching Contributions is forfeited to the Plan. Forfeitures are used to pay for
administrative  expenses  incurred  by the  Plan or used on an  annual  basis to
reduce  the  total  amount  of  Matching  Contributions  made to the Plan by the
Employer.

     Plan Termination

     Although it has not  expressed  any intent to do so, the  Employer  has the
right under the Plan,  subject to the provisions of ERISA,  to  discontinue  its
contributions  at any time or to terminate  the Plan. In the event of the Plan's
termination  or the complete  discontinuance  of Matching  Contributions  to the
Plan, participants will immediately become fully vested in their accounts.


                                       9







          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                          NOTES TO FINANCIAL STATEMENTS
                           December 31, 2004 and 2003


Note 2.     Summary of Significant Accounting Policies

     Basis of Presentation

     The accompanying  financial statements have been prepared under the accrual
basis  of  accounting  in  accordance  with  United  States  generally  accepted
accounting principles ("GAAP").

     Payment of Benefits

     Benefit payments made to participants are recorded when paid.

     Investment Valuation

     The Plan's  investments  are stated at fair value in the  Statements of Net
Assets Available for Benefits as of December 31, 2004 and 2003, as determined by
the Trustee. Investment fair values are determined as follows:

1.   Investments  in  registered  investment  company  funds  are  valued  using
     published  market  prices which  represent the net asset value of shares or
     units held by the Plan as of December 31.

2.   Investments  in  common/collective  trusts are  valued  based upon the fair
     values of the  underlying  net assets of the trusts,  as  determined by the
     Trustee.

3.   Investments  in the Company's  common stock are valued at the last reported
     sales price on December 31.

4.   Participants loans receivable are valued at their unpaid principal balance,
     which approximates fair value.

     Security Transactions and Investment Income

     Security  transactions  are accounted for on a trade-date  basis.  Expenses
incurred with transactions,  if any, are added to the purchase price or deducted
from the  selling  price at the time of the  transactions.  Dividend  income  is
recorded on the  ex-dividend  date.  Interest income is recorded as earned on an
accrual basis.

     Use of Estimates

     The preparation of the accompanying financial statements in conformity with
GAAP requires the Plan's  management to make  estimates  that affect the amounts
reported in the financial  statements  and  accompanying  notes.  Actual results
could differ from those estimates.


                                       10








          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                          NOTES TO FINANCIAL STATEMENTS
                           December 31, 2004 and 2003


Note 3.     Investments

     The  Trustee  holds the Plan's  investments  and  executes  all  investment
transactions.

     During  the year  ended  December  31,  2004,  the fair value of the Plan's
investments  (including  investments  purchased,  sold and held)  appreciated as
follows:


                                                                      
       Registered investment company funds....................   $ 9,625,680
       Common/collective trusts...............................       698,746
       Pioneer Stock Fund.....................................       540,093
                                                                  ----------
           Net appreciation in fair value of investments......   $10,864,519
                                                                  ==========


     The fair values of the Plan's  investments are subject to a number of risks
and uncertainties.  These risks and uncertainties  include,  among other things,
interest rate risk,  credit risk,  political  risk,  general  business risks and
overall  market  volatility  risk.  As  described in Note 1,  participants  have
investment  options to which they may allocate their  contributions  and account
balances. Those investment options have individual risk profiles that cause them
to  respond  differently  to changes  in the risks and  uncertainties  described
above.  Due to the level of risk associated with the Plan's  investments,  it is
reasonably  possible that changes in the fair values of the Plan investments may
occur  during the near term,  and that such  changes  could cause the Plan's net
assets available for benefits and the  participants'  account balances to differ
materially from those reported as of December 31, 2004.

Note 4.     Administrative Expenses

     The Employer may pay certain  expenses  incurred in the  establishment  and
administration of the Plan,  including expenses and fees of the Trustee,  but is
not obligated to do so. Any Plan expenses not paid by the Employer are paid from
the Plan's  earnings  or from  qualifying  account  forfeitures.  Administrative
expenses  paid by the Plan were $30,633 for  activity  related to the year ended
December 31, 2004, of which $25,613 was paid via qualifying  account  forfeiture
balances and $5,020 was paid via Plan earnings for participant  loan transaction
fees. Of the amounts paid via qualifying  account forfeiture  balances,  $12,620
was accrued at December 31, 2004. In addition to administrative expenses paid by
the Plan,  Plan  administrative  expenses  paid by the Employer were $22,736 for
activity related to the year ended December 31, 2004.

     Account  forfeiture  balances in the Plan  qualifying  to be used to defray
future Plan administrative expenses totaled $52,190 as of December 31, 2004.

Note 5.     Tax Status of the Plan

     The Plan has  received a  determination  letter from the  Internal  Revenue
Service  ("IRS") dated March 19, 2003,  stating that the Plan is qualified under
Section  401(a) of the Code and,  therefore,  the  related  trust is exempt from
taxation.  Subsequent  to this  determination  by the IRS, the Plan was amended.
Once  qualified,  the Plan is required to operate in conformity with the Code to
maintain its  qualification.  The Plan  Administrator has indicated that it will
take the necessary steps, if any, to maintain the Plan's qualified status.


                                       11








          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                          NOTES TO FINANCIAL STATEMENTS
                           December 31, 2004 and 2003


Note 6.     Related Party Transactions

     Certain Plan  investments  are in shares or units of registered  investment
company funds and common  /collective  trusts that are managed by the Trustee or
for which the Trustee provides services.  These funds and the Pioneer Stock Fund
qualify as party-in-interest transactions.

Note 7.     Reconciliation of Financial Statements to Form 5500

     The following is a reconciliation  of net assets available for benefits per
the financial statements to Form 5500:


                                                                          December 31,
                                                                  ----------------------------
                                                                      2004            2003
                                                                  ------------    ------------
                         
   Net assets available for benefits per the accompanying
       financial statements....................................   $129,196,835    $108,732,537
   Amounts due to withdrawing participants.....................            -          (139,599)
                                                                   -----------     -----------
       Net assets available for benefits per Form 5500.........   $129,196,835    $108,592,938
                                                                   ===========     ===========


     The following is a reconciliation  of distributions to participants  during
the year ended December 31, 2004, per the financial statements to Form 5500:

                                                               
   Distributions to participants per the accompanying
       financial statements....................................   $  3,695,734
   Less: Amounts due to withdrawing participants at
       December 31, 2003.......................................       (139,599)
                                                                   -----------
       Distributions to participants per Form 5500.............   $  3,556,135
                                                                   ===========


     Amounts  due to  withdrawing  participants  are  recorded  on Form 5500 for
distributions to participants  that have been processed and approved for payment
prior to December 31, but remained unpaid as of that date.



                                       12











          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN


         Schedule H; Line 4i - Schedule of Assets (Held At End of Year)
                                 EIN: 75-2516853
                                Plan Number: 001

                             As of December 31, 2004


                                                             (c)
                                                        Description of
                      (b)                           investment including
              Identity of issuer,                  maturity date, rate of                   (e)
               borrower, lessor,                  interest, collateral, par               Current
 (a)           or similar party                       or maturity value                    Value
----   --------------------------------     --------------------------------------     -------------
                                                                                 
  *    Vanguard Fiduciary Trust Company     Vanguard PRIMECAP Fund -
                                               544,742 shares                          $ 33,937,417
  *    Vanguard Fiduciary Trust Company     Vanguard Windsor II Fund -
                                               587,435 shares                            18,051,885
  *    Vanguard Fiduciary Trust Company     Vanguard 500 Index Fund -
                                               156,520 shares                            17,473,864
  *    Vanguard Fiduciary Trust Company     Vanguard Prime Money Market Fund -
                                               9,872,070 shares                           9,872,070
  *    Vanguard Fiduciary Trust Company     Vanguard Short-Term Investment-Grade
                                               Fund - 577,329 shares                      6,154,323
  *    Vanguard Fiduciary Trust Company     Vanguard Retirement Savings Trust -
                                               4,745,263 shares                           4,745,263
  *    Vanguard Fiduciary Trust Company     Vanguard Explorer Fund -
                                               62,552 shares                              4,664,506
  *    Vanguard Fiduciary Trust Company     Vanguard International Growth Fund -
                                               198,470 shares                             3,743,138
  *    Vanguard Fiduciary Trust Company     Vanguard Total Bond Market Index Fund -
                                               359,765 shares                             3,694,790
  *    Vanguard Fiduciary Trust Company     Vanguard Asset Allocation Fund -
                                               144,027 shares                             3,537,314
  *    Vanguard Fiduciary Trust Company     Vanguard Inflation-Protected Securities
                                               Fund - 214,284 shares                      2,693,544
  *    Fayez Sarofim & Co.                  Sarofim Equity Fund -
                                               247,027 shares                            12,558,831
  *    Pioneer Natural Resources Company    Pioneer Stock Fund - 448,249 units            5,652,423
  *    Participants loans receivable        Interest rates range from 5.0% to 10.5%       2,420,298
                                                                                        -----------
                                                                                       $129,199,666
                                                                                        ===========


--------------------------
*Party-in-interest

Note: Column (d) is not applicable since all investments are participant directed.





                                       13












          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                               S I G N A T U R E S


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

                            PIONEER NATURAL RESOURCES USA, INC.
                            401(k) AND MATCHING PLAN


Date:  June 28, 2005        By:   /s/ Larry N. Paulsen
                                 -----------------------------------------------
                                 Larry N. Paulsen
                                 Chairman of Pioneer Natural Resources USA, Inc.
                                 401(k) and Matching Plan Committee


Date:  June 28, 2005        By:   /s/ Richard P. Dealy
                                 -----------------------------------------------
                                 Richard P. Dealy
                                 Member of Pioneer Natural Resources USA, Inc.
                                 401(k) and Matching Plan Committee


Date:  June 28, 2005        By:   /s/ Kerry D. Scott
                                 -----------------------------------------------
                                 Kerry D. Scott
                                 Member of Pioneer Natural Resources USA, Inc.
                                 401(k) and Matching Plan Committee


Date:  June 28, 2005        By:   /s/ Kevin Schepel
                                 -----------------------------------------------
                                 Kevin Schepel
                                 Member of Pioneer Natural Resources USA, Inc.
                                 401(k) and Matching Plan Committee


Date:  June 28, 2005        By:   /s/ David W. Simpson
                                 -----------------------------------------------
                                 David W. Simpson
                                 Member of Pioneer Natural Resources USA, Inc.
                                 401(k) and Matching Plan Committee


Date:  June 28, 2005        By:   /s/ Susan A. Spratlen
                                 -----------------------------------------------
                                 Susan A. Spratlen
                                 Member of Pioneer Natural Resources USA, Inc.
                                 401(k) and Matching Plan Committee




                                       14











          PIONEER NATURAL RESOURCES USA, INC. 401(k) AND MATCHING PLAN

                                INDEX TO EXHIBITS



Exhibit
Number                               Description                          Page
-------                              -----------                          ----

 23.1 (a)     Consent of Independent Registered Public Accounting Firm     16


--------------
(a)   Filed herewith





                                       15