EXHIBIT 21 SUBSIDIARIES OF THE REGISTRANT Percentage of Voting Securities Owned by Organized Immediate Name of Company Under Laws of Parent --------------- ------------- ------------- Atlantic Richfield Company (Registrant)........... Delaware Subsidiaries of Registrant in consolidated financial statements, as of December 31, 2000: Vastar Resources, Inc. ......................... Delaware 100.0 ARCO British Limited............................ Delaware 100.0 The subsidiaries whose names are not listed above, if considered in the aggregate as a single subsidiary, would not constitute a significant subsidiary.