<Page> EXHIBIT 21.1 ARQULE, INC. SUBSIDIARIES OF THE COMPANY ArQule Catalytics, Inc., a corporation organized under the laws of the State of Delaware (dissolved on March 1, 2001). Camitro Corporation, a corporation organized under the laws of the State of California. Camitro UK, Ltd., a company organized under the laws of the United Kingdom (Camitro UK, Ltd. is a subsidiary of Camitro Corporation). ArQule International, Inc., a company organized under the laws of Barbados, West Indies.