The occurrence of pancreatic pleural effusion, secondary to an internal pancreatic fistula, is a rare clinical syndrome and diagnosis is often missed. The key to the diagnosis is a dramatically elevated pleural fluid amylase. This pancreatic pleural effusion is also called a pancreatic pleural fistula. It is characterized by profuse pleural fluid and has a tendency to recur. Here we report a case of delayed internal pancreatic fistula with pancreatic pleural effusion emerging after splenectomy. From the treatment of this case, we conclude that the symptoms and signs of a subphrenic effusion are often obscure; abdominal computed tomography may be required to look for occult, intra-abdominal infection; and active conservative treatment should be carried out in the early period of this complication to reduce the need for endoscopy or surgery.