Pancreatitis was induced by injection of autologous bile into the main pancreatic duct of dogs. An initial fall in blood pressure was accompanied by appearance of large quantities of active trypsin, chymotrypsin, and elastase in pancreatic exudate with full saturation of protease inhibitors. The enzymes soon appeared in ascitic fluid and lymph, but only in the form of complexes with alpha1-antitrypsin, and alpha2-macroglobulin. No such complexes were detected in venous blood indicating short half-life in the circulation. These studies confirm the release of pancreatic enzymes during bile-induced pancreatitis, and quantify an important protective role for plasma protease inhibitors in this situation.