EXHIBIT 21 LIST OF SIGNIFICANT SUBSIDIARIES Anadarko E&P Company LP a Delaware limited partnership, Anadarko Holding Company a Utah corporation, Anadarko Canada Resources an Alberta partnership, Anadarko Land Corp. a Nebraska corporation, Anadarko Algeria Company, LLC a Delaware limited liability company, Anadarko Energy Services Company a Delaware corporation, APC Venezuela, S.R.L. a Venezuela limited liability company,