3-Benzylazetidine-2-one derivatives were designed and evaluated as a novel series of chymase inhibitors. Structure-activity relationship studies of 3-benzylazetidine-2-ones led to compounds 23, which exhibited 3.1 nM inhibition of human chymase and enhancement of stability in human plasma (t(1/2) 6 h). (C) 2001 Elsevier Science Ltd. All rights reserved.