A case of chronic pancreatic pleural effusions is reported. The effusions were massive in the right chest at first and became bilateral. Endoscopic retrograde pancreatography showed a pancreatic pleural fistula toward the diaphragm. Computed tomography after endoscopic retrograde pancreatography revealed the entire course of the fistula and a mediastinal pseudocyst. Computed tomography and the operative fistulogram did not show immediate leakage of the contrast medium from the mediastinal pseudocyst.