EXHIBIT 21.1

SUBSIDIARIES OF THE COMPANY
as of December 31, 2005

State or Jurisdiction
of Organization	Subsidiaries	Ownership %
Delaware	DMLP CO.		100.0
Colorado	Long Canyon Gas Company, LLC		75.4
Colorado	Lorencito Gas Gathering, LLC		85.0
Delaware	Mesa Environmental Ventures Co.		100.0
Delaware	Parker & Parsley Argentina, Inc.		100.0
South Africa	Petroleum South Cape (Pty) Ltd.		100.0
Canada	Pioneer Canada ULC		100.0
Canada	Pioneer Energy Canada Ltd.		100.0
Delaware	Pioneer International Resources Company		100.0
Nigeria	Pioneer JDZ Limited		100.0
Texas	Pioneer Natural Gas Company		100.0
Delaware	Pioneer Natural Resources Alaska, Inc.		100.0
Cayman Islands	Pioneer Natural Resources Algeria Limited		100.0
Cayman Islands	Pioneer Natural Resources Anaguid Ltd.		100.0
Argentina	Pioneer Natural Resources (Argentina) S.A.		100.0
Canada	Pioneer Natural Resources Canada		100.0
Canada	Pioneer Natural Resources Canada Inc.		100.0
Cayman Islands	Pioneer Natural Resources Equatorial Guinea Limited		100.0
Texas	Pioneer Natural Resources Foundation		100.0
Bahamas	Pioneer Natural Resources Libya Limited		100.0
Cayman Islands	Pioneer Natural Resources Morocco Limited		100.0
Nigeria	Pioneer Natural Resources Nigeria (320) Limited		58.8
Cayman Islands	Pioneer Natural Resources Nigeria Ltd.		100.0
Delaware	Pioneer Natural Resources Properties LP		100.0
South Africa	Pioneer Natural Resources South Africa (Pty) Limited		100.0
Argentina	Pioneer Natural Resources (Tierra Del Fuego) S.A.		100.0
Cayman Islands	Pioneer Natural Resources Tunisia Ltd.		100.0
United Kingdom	Pioneer Natural Resources UK Limited		100.0
Delaware	Pioneer Natural Resources USA, Inc.		100.0
Nigeria	Pioneer Nigeria Deepwater Limited		100.0
Nigeria	Pioneer NR Nigeria (256) Limited		100.0
Cayman Islands	Pioneer Resources Africa Limited		100.0
Bahamas	Pioneer Resources Gabon Limited		100.0
Delaware	Pioneer Shelf Properties Incorporated		100.0
Texas	Pioneer Uravan, Inc.		100.0
Delaware	Westpan NGL LP		100.0
Delaware	Westpan Properties, Inc.		100.0
Nevada	Westpan Resources Company		100.0
Delaware	Westpan Resources LP		100.0
	Partnerships that Pioneer Natural Resources USA, Inc. is the managing general partner
Texas	Parker & Parsley 87-A Conv., Ltd.
Delaware	Parker & Parsley Private Investment 88 L.P.
Delaware	Parker & Parsley Private Investment 89, L.P.
Delaware	Parker & Parsley 90 Spraberry Private Development, L.P.
Texas	Midkiff Development Drilling Program, Ltd.
Texas	Mesa Offshore Royalty Partnership