July 15, 2005

VIA FACSIMILE and U.S. Mail

Mr. Richard P. Dealy
Executive Vice President and Chief Financial Officer
Pioneer Natural Resources Company
5205 N. O`Connor Blvd.  Suite 900
Irving, TX  75039

Re:    Pioneer Natural Resources Company
Form 10-K, Filed February 22, 2005
File No.1-13245

Dear Mr. Dealy:

We have reviewed your April 27, 2005 response letter and have the
following
engineering comments.  Where comments ask for supplemental
information,
please provide us with that information within 10 business days of
the date
of this letter.  Comply with the remaining comments in your future
filings.
If you disagree with any of these comments, we will consider your
explanation as to why our comment is inapplicable or a revision is
unnecessary.  Please be as detailed as necessary in your
explanation.
In some of our comments, we may ask you to provide us with
supplemental
information so we may better understand your disclosure.  After
reviewing
this information, we may or may not raise additional comments.

Please understand that the purpose of our review process is to
assist
you
in your compliance with the applicable disclosure requirements and
to
enhance the overall disclosure in your filing.  We look forward to
working
with you in these respects.  We welcome any questions you may have
about our comments or on any other aspect of our review.  Feel
free
to call
us at the telephone numbers listed at the end of this letter.

2004 10-K for the year ended December 31, 2004

Business, page 5

Evergreen Merger, page 5

1.  Your response 1a) does not address the minimum gas production
rates you require for attributing proved reserves to newly drilled
exploration locations.  Please tell us how you determine that
proved
reserves are justified in such situations.

2.  In your response 1b), you state, "The primary exception to
this
case
would be that of an infill well which is drilled later in the life
of
the
reservoir, where significant pressure drawdown has occurred and
free
gas saturation is present. In these cases, a well will more
typically
see
its peak gas rate when it begins to produce and decline
thereafter,
more
like a conventional gas well."  Please explain your methodology in
accounting for the reduced gas-in-place in such infill wells`
proved
reserve estimates.  Clarify whether the isotherms to which you
refer
in response 1d) are derived from desorption measurements.  If you
have
used adsorption data in your estimates, address how you avoid
overestimation of coal bed gas content if coal beds are
undersaturated
as has been observed in the Powder River Basin.

3.  In your response 1d), you state, "The volumetric recoverable
reserves are
then used to constrain the individual well forecasts on a spacing
unit by
spacing unit basis, typically 160 acres. Drainage areas are not
explicitly
estimated for each well."  This implies that you attribute 160
acres`
proved reserves to the spacing unit`s well and, presumably, to its
offsetting
proved undeveloped locations.  If the well`s drainage area - and
thus
its
ultimate proved reserves - is materially lower, this
overestimation
is
leveraged in its offsetting PUD locations and a significant error
can result.  Please support your drainage area assumptions for the
Evergreen coal bed methane properties` proved reserve estimates.

Reserve Quantity Information, page 107

4.  In response 9, you state, "In the case of these seven non-
offsetting
PUDs, the areas are all "windows" within the existing field which
have not yet been developed. Based upon above, the Company
believes
that these PUD locations are appropriately reflected in its proved
reserves."  Please affirm to us that you have established pressure
communication across all these undeveloped "windows".

Closing Comments

As appropriate, please amend your future documents in response to
these
comments.  You may wish to provide us with marked copies of the
documents
to expedite our review.  Please furnish a cover letter that keys
your
responses to our comments and provides any requested supplemental
information.
Detailed cover letters greatly facilitate our review.
Please understand that we may have additional comments after
reviewing
your document(s) and responses to our comments.

Please direct questions regarding engineering issues and
related disclosures to Ronald Winfrey at (202) 942-1778.  In his
absence,
please contact the undersigned at (202) 942-1870.

							Sincerely,

							H. Roger Schwall
							Assistant Director