EXHIBIT 21 SUBSIDIARIES OF UNITED INDUSTRIAL CORPORATION March 3, 1998 State Approximate Percentage of (or jurisdiction) Voting Securities Owned by Name in which Incorporated Immediate Parent - ----------------------------------------------------------------------------------------------------------------------------- AAI Corporation Maryland 100% (a) A.A.I. Engineering Support, Inc. Maryland 100 (b) A.A.I. International, Inc. Delaware 100 (b) Seti, Inc. Pennsylvania 100 (b) AAI Medical, Inc. Maryland 100 (b) AAI MICROFLITE Simulation International Corporation Maryland 100 (b) AAI/ACL Technologies, Inc. Maryland 100 (b) AAI California Carshells, Inc. Maryland 100 (b) Detroit Stoker Company Michigan 100 (a) Midwest Metallurgical Laboratory, Inc. Michigan 100 (c) UIC Products Co. Illinois 100 (a) Symtron Systems, Inc. New Jersey 100 (a) U.I.C.-Del. Corporation Delaware 100 (a) U.I.C. International, Ltd. Barbados 100 (a) - ------------------ (a) Percentage owned by United Industrial Corporation ("United). (b) Percentage owned by AAI Corporation. (c) Percentage owned by Detroit Stoker Company. All of the subsidiaries listed above are included in the consolidated financial statements of United.