Several carboxylate derivatives with variation at the P1' residue were synthesized and evaluated as stromelysin (MMP-3) inhibitors. Compounds containing a biphenyl moiety at P1' were found to be potent inhibitors of MMP-3. An X-ray crystal structure of the most potent compound, carboxylate 19, revealed an important interaction between the inhibitor's biphenyl and histidine 224 in the S1' pocket of MMP-3. (C) 1997 Elsevier Science Ltd.