EXHIBIT 21 SUBSIDIARIES OF THE REGISTRANT DECEMBER 31, 1996 State or Country Name of Incorporation Domestic AH Investments Ltd. Delaware A.H. Robins Company, Incorporated Delaware AHP Subsidiary Holding Corporation Delaware American Cyanamid Company Maine Ayerst Laboratories Incorporated New York Ayerst-Wyeth Pharmaceuticals Incorporated Delaware Cyanamid Agricultural de Puerto Rico, Inc. New Jersey Cyanamid International Corporation Limited Delaware ESI Lederle Inc. Delaware Genetics Institute, Inc. Delaware Immunex Corporation Washington Lederle Parenterals, Inc. New Jersey Lederle Piperacillin, Inc. New Jersey Quinton Instrument Company Washington Route 24 Holdings, Inc. Delaware Sherwood Medical Company Delaware Wyeth Laboratories Inc. New York Foreign AHP Manufacturing B.V. Netherlands American Home Products Holding (UK) plc Great Britain Cyanamid Finance B.V. Netherlands Cyanamid GmbH Germany Cyanamid Iberica, S.A. Spain State or Country Name of Incorporation Cyanamid Italia, S.p.A. Italy Cyanamid (Japan), Ltd. Japan Cyanamid of Great Britain Limited Great Britain Cyanamid Quimica do Brasil Ltda. Brazil Cyanamid Taiwan Corporation Taiwan Dimminaco AGSA Ltd Switzerland John Wyeth & Brother Limited Great Britain Laboratorios Wyeth-Whitehall Ltda. Brazil L.W. Investments Limited Bermuda Nippon Sherwood Medical Industries Ltd. Japan Wyeth (Japan) Corporation Japan Wyeth Australia Pty. Limited Australia Wyeth-Ayerst Canada Inc. Canada Wyeth-Lederle France Wyeth-Pharma G.m.b.H. Germany Wyeth Philippines, Inc. Philippines There have been omitted from the above list the names of subsidiaries which, considered in the aggregate as a single subsidiary, would not constitute a significant subsidiary.