SECURITIES AND EXCHANGE COMMISSION
                      Washington, D.C.  20549

                            SCHEDULE 13G
             Under the Securities Exchange Act of 1934

                         (Amendment No. 1)*

                 Pioneer Natural Resources Company
             ------------------------------------------
                          (Name of Issuer)


                            Common Stock
            -------------------------------------------
                  (Title of Class and Securities)

                             723787107
             --------------------------------------------
               (CUSIP Number of Class of Securities)



* The remainder of this cover page shall be filled out for a

reporting person's initial filing on this form with respect to the

subject class of securities, and for any subsequent amendment

containing information which would alter the disclosures provided

in a prior page.



The information required in the remainder of this cover page shall

not be deemed to be "filed" for the purpose of Section 18 of the

Securities Exchange Act of 1934 ("Act") or otherwise subject to the

liabilities of that section of the Act but shall be subject to all

other provisions of the Act (however, see the Notes).






                  (Continued on following page(s))


CUSIP No. 723787107                                    13G
- -------------------------------------------------------------------
(1)  NAMES OF REPORTING PERSONS
     Southeastern Asset Management, Inc.      I.D. No. 62-0951781
- -------------------------------------------------------------------
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
- -------------------------------------------------------------------
(3)  SEC USE ONLY
- -------------------------------------------------------------------
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Tennessee
- -------------------------------------------------------------------
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
                                   :    9,718,300 shares
NUMBER OF SHARES BENEFICIALLY
OWNED BY EACH REPORTING PERSON     --------------------------------
WITH                               :(6) SHARED OR NO VOTING POWER
                                   :    8,000,000 shares (Shared)
                                        2,153,000 shares (No Vote)
                                   --------------------------------
                                   :(7) SOLE DISPOSITIVE POWER
                                        (Discretionary Accounts)
                                   :    11,832,300 shares
                                   --------------------------------
                                   :(8) SHARED OR NO DISPOSITIVE
                                        POWER
                                   :    8,000,000 shares (Shared)
                                           39,000 SHARES (None)
- -------------------------------------------------------------------
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
      (Discretionary Voting or Disposition)
       19,871,300 shares
- -------------------------------------------------------------------
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES -X- See Items 4(c)(ii) and (iv)
- -------------------------------------------------------------------
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
      19.8 %
- -------------------------------------------------------------------
(12)  TYPE OF REPORTING PERSON
      IA
- -------------------------------------------------------------------








CUSIP No.  723787107                                    13G
- -------------------------------------------------------------------
(1)  NAMES OF REPORTING PERSONS
     Longleaf Partners Fund                   I.D. No. 63-6147721
- -------------------------------------------------------------------
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
- -------------------------------------------------------------------
(3)  SEC USE ONLY
- -------------------------------------------------------------------
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Massachusetts business trust
- -------------------------------------------------------------------
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
                                   :    None
NUMBER OF SHARES BENEFICIALLY
OWNED BY EACH REPORTING PERSON     --------------------------------
WITH                               :(6) SHARED VOTING POWER

                                   :    8,000,000 shares
                                   --------------------------------
                                   :(7) SOLE DISPOSITIVE POWER
                                   :    (Discretionary Accounts)
                                   :     None
                                   --------------------------------
                                   :(8) SHARED DISPOSITIVE POWER

                                   :    8,000,000 shares
- -------------------------------------------------------------------
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        8,000,000 shares
- -------------------------------------------------------------------
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
- -------------------------------------------------------------------
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
       8.0 %
- -------------------------------------------------------------------
(12)  TYPE OF REPORTING PERSON
      IV
- -------------------------------------------------------------------










CUSIP No. 723787107                                  13G
- -------------------------------------------------------------------
(1)  NAMES OF REPORTING PERSONS
     O. Mason Hawkins                         I.D. No. 257-72-3256
- -------------------------------------------------------------------
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
- -------------------------------------------------------------------
(3)  SEC USE ONLY
- -------------------------------------------------------------------
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Citizen of United States
- -------------------------------------------------------------------
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
                                   :    None
NUMBER OF SHARES BENEFICIALLY
OWNED BY EACH REPORTING PERSON     --------------------------------
WITH                               :(6) SHARED VOTING POWER

                                   :    None
                                   --------------------------------
                                   :(7) SOLE DISPOSITIVE POWER

                                   :    None
                                   --------------------------------
                                   :(8) SHARED DISPOSITIVE POWER

                                   :    None
- -------------------------------------------------------------------
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

       None  (See Item 3 )
- -------------------------------------------------------------------
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
- -------------------------------------------------------------------
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
      0.0%
- -------------------------------------------------------------------
(12)  TYPE OF REPORTING PERSON
      IN
- -------------------------------------------------------------------









Item 1.

     (a). Name of Issuer: Pioneer Natural Resources Company
           ("Issuer")

     (b). Address of Issuer's Principal Executive Offices:

          1400 Williams Square West
          5205 N. O'Connor Blvd.
          Irving, TX 75039

Item 2.

     (a) and (b). Names and Principal Business Addresses of Persons
         Filing:

         (1). Southeastern Asset Management, Inc.
              6410 Poplar Ave., Suite 900
              Memphis, TN 38119

         (2). Longleaf Partners Fund
              6410 Poplar Ave., Suite 900
              Memphis, TN 38119

         (3). Mr. O. Mason Hawkins
              Chairman of the Board and C.E.O.
              Southeastern Asset Management, Inc.
              6410 Poplar Ave. Suite 900
              Memphis, TN 38119


     (c). Citizenship:

          Southeastern Asset Management, Inc. - A Tennessee
            corporation

          Longleaf Partners Fund, a series of Longleaf Partners
            Funds Trust, a Massachusetts business trust

          Mr. O. Mason Hawkins - U.S. Citizen

     (d). Title of Class of Securities:  Common Stock, (the
            "Securities").

     (e). Cusip Number: 723787107


Item 3.  If this statement is filed pursuant to Rules 13d-1 (b) or
 13d-2 (b), check whether the person filing is a:

     (d). Investment Company registered under Sec. 8 of the
          Investment Company Act- Longleaf Partners Fund, a series
          of Longleaf Partners Funds Trust.

     (e). Investment Advisor registered under Section 203 of the
          Investment Advisers Act of 1940.  This statement is being
          filed by Southeastern Asset Management, Inc. as a
          registered investment adviser. All of the securities
          covered by this report are owned legally by
          Southeastern's investment advisory clients and none are
          owned directly or indirectly by Southeastern.  As
          permitted by Rule 13d-4, the filing of this statement
          shall not be construed as an admission that Southeastern
          Asset Management, Inc. is the beneficial owner of any of
          the securities covered by this statement.

     (g). Parent Holding Company.  This statement is also being
          filed by Mr. O. Mason Hawkins, Chairman of the Board and
          Chief Executive Officer of Southeastern Asset Management,
          Inc. in the event he could be deemed to be a controlling
          person of that firm as the result of his official
          positions with or ownership of its voting securities. The
          existence of such control is expressly disclaimed.  Mr.
          Hawkins does not own directly or indirectly any
          securities covered by this statement for his own account.
          As permitted by Rule 13d-4, the filing of this statement
          shall not be construed as an admission that Mr. Hawkins
          is the beneficial owner of any of the securities covered
          by this statement.

Item 4. Ownership:

     (a). Amount Beneficially Owned: (At July 31, 1998)
          19,871,300 shares

     (b). Percent of Class: 19.8 %. Percentage is based on
          100,444,593 shares of Common Stock outstanding at June 1,
          1998, per information supplied by the Issuer.

     (c). Number of shares as to which such person has:

          (i).   sole power to vote or to direct the vote:
                 9,718,300 shares

          (ii).  shared or no power to vote or to direct the vote:

                 Shared - 8,000,000 shares owned by Longleaf
                 Partners Fund, a series of Longleaf Partners Funds
                 Trust, an open-end management investment company
                 registered under the Investment Company Act of
                 1940.

                 No Power to Vote - 2,153,000. This figure does not
                 include 7,000 shares held by a completely non-
                 discretionary account over which the filing
                 parties have neither voting nor dispositive power
                 and for which the filing parties disclaim
                 beneficial ownership.

          (iii). sole power to dispose or to direct the disposition
                 of: 11,832,300 shares

          (iv).  shared or no power to dispose or to direct the
                 disposition of:

                 Shared - 8,000,000 shares owned by Longleaf
                 Partners Fund, a series of Longleaf Partners Funds
                 Trust, an open-end management investment company
                 registered under the Investment Company Act of
                 1940.

                 No Power - 39,000 shares.  This figure does not
                 include 7,000 shares held by a completely non-
                 discretionary account over which the filing
                 parties have neither voting nor dispositive power
                 and for which the filing parties disclaim
                 beneficial ownership.

Item 5. Ownership of Five Percent or Less of a Class:  N/A

Item 6. Ownership of More Than Five Percent on Behalf of Another
        Person:  N/A

Item 7. Identification and Classification of the Subsidiary Which
        Acquired the Security Being Reported on By the Parent
        Holding Company:  N/A

Item 8. Identification and Classification of Members of the Group:
        N/A

Item 9. Notice of Dissolution of Group:  N/A

Item 10. Certification:

By signing below I certify that, to the best of my knowledge and
belief, the securities referred to above were acquired in the
ordinary course of business and were not acquired for the purpose
and do not have the effect of changing or influencing the control
of the issuer of such securities and were not acquired in
connection with or as a participant in any transaction having such
purposes or effect.







                             Signatures

After reasonable inquiry and to the best of the knowledge and
belief of the undersigned, the undersigned certifies that the
information set forth in this statement is true, complete, and
correct.

Dated: August 6, 1998

Southeastern Asset                   Longleaf Partners Fund
Management, Inc.

By  /s/ Charles D. Reaves         By  /s/ Charles D.  Reaves
- ---------------------------       --------------------------
Charles D. Reaves                    Charles D. Reaves
Vice President and                   Executive Vice President
  General Counsel


O. Mason Hawkins, Individually

/s/ O. Mason Hawkins
- -----------------------

                       Joint Filing Agreement


In accordance with Rule 13d-1(f) under the Securities Exchange Act
of 1934, the persons or entities named below agree to the joint
filing on behalf of each of them of this Schedule 13G with respect
to the Securities of the Issuer and further agree that this joint
filing agreement be included as an exhibit to this Schedule 13G. In
evidence thereof, the undersigned hereby execute this Agreement as
of the 6th day of August, 1998.

Southeastern Asset                   Longleaf Partners Fund
Management, Inc.

By  /s/ Charles D. Reaves         By  /s/ Charles D.  Reaves
- ---------------------------       --------------------------
Charles D. Reaves                    Charles D. Reaves
Vice President and                   Executive Vice President
  General Counsel


O. Mason Hawkins, Individually

/s/ O. Mason Hawkins
- -----------------------




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