EXHIBIT 99.1



                                  NEWS RELEASE

                    Investor Relations Contact: Susan Spratlen   (972) 444-9001


              Pioneer Announces First Production from Falcon Field,
                        Approves Harrier Development and
           Acquires Additional Interest in Falcon and Related Projects

Dallas,  Texas, March 31, 2003 -- Pioneer Natural Resources Company  ("Pioneer")
(NYSE:PXD) today announced that the Pioneer-operated Falcon field in the western
deepwater  Gulf of Mexico  began  producing  on March  15,  2003.  The  two-well
development is currently  producing  approximately 185 million cubic feet of gas
and 650 barrels of condensate per day. Pioneer also announced that, as part of a
broader  transaction  discussed below, it has acquired its partner's 25% working
interest in the Falcon field and related  projects and now owns 100%.  The field
is Pioneer's first operated deepwater project, and first production was achieved
two weeks ahead of schedule with less capital investment than was budgeted.

Pioneer has  acquired  the  remaining  interest in 32 blocks in the Falcon area,
including the Falcon field,  the Harrier field and related  satellite  prospects
from Mariner Energy  ("Mariner")  for a net cash payment of  approximately  $113
million including normal closing  adjustments.  Pioneer has also assumed certain
contractual  obligations from Mariner. The transaction was approved by Mariner's
board of directors and was closed on Friday,  March 28, 2003,  with payment into
escrow.  The transfer from escrow is  contingent  upon receipt of a no objection
notice from the  creditors  committee  of Enron Corp,  which owns an interest in
Mariner.

Pioneer  also  announced  that it has approved  the  development  of the Harrier
discovery  as a  single-well  subsea  tie-back to the Falcon  field  facilities.
Pioneer  now  owns a 100%  working  interest  in the  Harrier  field  which  has
estimated gas reserves of 55 to 80 billion  cubic feet.  An additional  parallel
pipeline  connecting the Falcon field to the Falcon Nest platform on the Gulf of
Mexico shelf will be added to the Falcon facilities doubling the capacity to 400
million  cubic feet of gas per day.  Pioneer  expects first gas from the Harrier
field  within nine months with  combined  daily gas  production  from Falcon and
Harrier  expected to reach 275 million  cubic feet per day. The Company plans to
drill  two  additional  prospects  in the  Falcon  area  during  2003  that,  if
successful,  could also be tied back to the Falcon  field to utilize  the excess
pipeline capacity. In addition,  Pioneer has a multi-year inventory of prospects
on the 32 blocks it holds in the area.

The Falcon  field is located  100 miles east of Corpus  Christi in 3,400 feet of
water in East Breaks 579/623.  The field and surrounding  satellite  discoveries
are being produced via subsea wells tied back to a host platform  located on the
shelf  approximately  30 miles  away.  The  platform,  Falcon  Nest,  and  other
facilities are owned and operated by El Paso Energy  Partners,  L.P. Pioneer has
drilled  three  satellite  wells in the Falcon  area  during  2003,  the Harrier
discovery  and two other wells that were  unsuccessful.  Falcon is the second of
five significant projects Pioneer plans to bring on stream through early 2004.

Scott D.  Sheffield,  Chairman  and CEO,  stated,  "With  Falcon on stream,  our
worldwide daily production is 50% higher than it was just one year ago, and U.S.
gas  production  is up 135%  over the same  period.  By  approving  the  Harrier
satellite  project for immediate  development,  we add significant value and gas
production  growth in 2004. The capital  invested in the additional  pipeline to
the Falcon Nest  platform  also  provides  added  capacity to more  aggressively
pursue  other  prospects in the area with the  potential to further  impact 2004
production and value."

Pioneer is a large  independent oil and gas  exploration and production  company
with operations in the United States, Canada, Argentina, South Africa, Gabon and
Tunisia.  Pioneer's  headquarters  are in Dallas.  For more  information,  visit
Pioneer's website at www.pioneernrc.com.





Except for  historical  information  contained  herein,  the  statements in this
Document  are  forward-looking  statements  that are made  pursuant  to the Safe
Harbor  Provisions  of the  Private  Securities  Litigation  Reform Act of 1995.
Forward-looking  statements  and  the  business  prospects  of  Pioneer  Natural
Resources  Company are subject to a number of risks and  uncertainties  that may
cause Pioneer's  actual results in future periods to differ  materially from the
forward-looking  statements.  These risks and uncertainties include, among other
things,   volatility  of  oil  and  gas  prices,   product  supply  and  demand,
competition,   government  regulation  or  action,  foreign  currency  valuation
changes,  foreign government tax and regulation changes,  litigation,  the costs
and results of drilling and operations,  Pioneer's  ability to replace reserves,
implement its business plans, or complete its development projects as scheduled,
access  to and cost of  capital,  uncertainties  about  estimates  of  reserves,
quality of  technical  data,  environmental  and weather  risks,  acts of war or
terrorism.  These  and other  risks are  described  in  Pioneer's  10-K and 10-Q
Reports and other filings with the Securities and Exchange Commission.