In a personal series of 188 patients with pancreatic disease referred for endoscopic retrograde cholangiography (ERCP), one or more ducts were cannulated in 168 patients; of the 168 patients; of the 168 patients, 19 had carcinoma and 149 had chronic pancreatitis. Abnormalities were found in 71 of the 149 patients with pancreatitis, either in the pancreatic duct, the bile duct, or both ducts. The demonstration of these abnormalities was of critical importance in planning the management of these patients. Ducts were normal in 78 patients. No benefit could be expected from operating upon these patients. It is concluded that approximately one half of the patients with chronic pancreatitis will have demonstrable lesions amenable to operation, and one half will not. ERCP is essential in the investigation and management of patients suspected of having chronic pancreatitis.