Mast cell protease-1 (MCPT-1), also known as β‑chymase, is a member of the Chymase family of chymotrypsin-like serine proteases and is the only chymase expressed by intestinal mucosal mast cells. Its activation is completed by the removal of a two residue N‑terminal propeptide by a dipeptidyl peptidase (Cathepsin C). Like human α‑Chymase, MCPT-1 is capable of the conversion of angiotensin I to angiotensin II, which plays a key role in the regulation of arterial pressure. MCPT-1 promotes mucosal permeability in intestinal allergic hypersensitivity reactions and plays an important role in host defense against intestinal parasites. Studies have shown that specific chymase inhibitors are able to diminish the development of abdominal aortic aneurysm and reduce the adhesion formation after cardiac surgery in hamsters. Therefore, the development of specific inhibitors of chymase activity has been a pharmacologic strategy to develop therapeutic agents.