A case of generalized peritonitis occurred eight months after a pylorus preserving pancreatoduodenectomy was experienced. The patient developed anastomotic leakage at the anastomosed site between the pan-creas and jejunum after the initial operation. The leakage was cured conservatively, but some mechanism of causing stricture at the anastomosed site might occur in the course of cure. A slight dilatation of the pancreatic duct in the remnant pancreas and segmental low density area in the parenchyma were confirmed. Local-ized pancreatitis due to impaired defluxion of pancreatic juice was thought. The patient presented with abrupt onset of abdominal pain during observation of clinical course after the operation on ambulant basis. An emergency operation was performed with a diagnosis of generalized peritonitis, when a great volume of purulent fluid retention with high level of amylase was found in the abdomen. Pronounced inflammation was noted in the vicinity of the remnant pancreatic tail on the posterior surface of the remnant stomach. We diagnosed the case as generalized peritonitis due to inflammation of the remnant pancreas. After the operation, a contaminated exudate with high amylase level which was not pure pancreatic juice was continuously drained from an indwelt drain on the gastric posterior surface, that offered a suspicion of breakdown of the pancreatic duct. It is thought that anastomotic leakage caused impaired defluxion of pancreatic juice to induce the inflammatory breakdown of the pancreatic duct, with an aid of increasing internal pressure of the intestine due to adhesion as well.