The spectrum of acute pancreatitis ranges from mild edematous disease to a severe necrotizing process which is usually accompanied by local or systemic complications and even mortality. Early deaths (within the first week) due to severe acute pancreatitis are generally caused by massive inflammatory responses which result in multiple organ failure. Although the exact mechanisms which trigger the inflammatory and necrotizing processes are not completely understood, it is generally accepted that autodigestion and activated leukocytes play important roles in the pathogenesis of acute pancreatitis. Proinflammatory cytokines are associated with systemic inflammatory response syndrome and multiple organ failure syndrome in acute pancreatitis. A compensatory anti-inflammatory response occurs in parallel with systemic inflammatory response syndrome. Trypsin secreted by the pancreatic acinar cells activates protease-activated receptor-2 which can result in the production of cytokines. Protease inhibitors such as aprotinin, gabexate mesilate, nafamostat mesilate, ulinastatin, etc. can inhibit the various enzymes and inflammatory response in experimental and clinical studies. Thus, protease inhibitors have been considered as a potential treatment to inhibit the pancreatic inflammation in acute pancreatitis. The beneficial effects of antiproteases on experimental severe acute pancreatitis may be, in part, due to the modulation of inflammatory cytokine responses. The effect of protease inhibitors on the inflammatory response in human acute pancreatitis deserves further study.