Pancreatitis when associated with biliary disease has a more promising prognosis than pancreatic inflammation of indefinite etiology. Gallstone pancreatitis is due to obstruction of the main pancreatic duct by a calculus, inflammatory reaction, or ampullary stenosis. This report is an attempt to present the natural history of this disease process and some new concepts regarding methods of diagnosis and treatment. Review of Cases Fifty-five patients with coexistent biliary disease and pancreatitis were treated on the Surgical Service at the Los Angeles County Harbor General Hospital from January, 1950, to December, 1959. There were 11 emergency cases with 5 deaths and 44 elective cases with 2 deaths (Table 1). The age range was from 19 to 85, and 19 patients were over 70 years of age (Table 2). Thirty-seven patients had a history of acute abdominal pain and six had a history of jaundice. There were ten patients with an antedated