Thirty-four cases of mediastinal pancreatic pseudocyst have been previously reported. Among the 32 previous reports with operative or autopsy analysis, communication has been identified in 30. Even when this communication has been quite small between the mediastinal fluid collection and the pancreas, the recommended operative strategy has been enteric drainage directly to this communicating tract. We report the case of a patient with a mediastinal pancreatic pseudocyst in whom the communication between the pancreas and the pseudocyst was not located. The condition was managed by drainage of the mediastinal pseudocyst with decompression of the main pancreatic duct by means of a longitudinal pancreaticojejunostomy in a patient with chronic pancreatitis.