In the 46-year period from September 1, 1932 to September 1, 1978, 11,808 patients were operated on for nonmalignant biliary tract disease. In 80.1% of these patients, the disease was considered chronic, and in 19.9%, acute inflammation was superimposed on the existing condition. There were 207 postoperative deaths, a mortality rate of 1.7%. Advanced age, acute cholecystitis and common duct stones were the principal determinants of operative mortality. Cholecystectomy for chronic cholecystitis was performed in 7,413 patients with an operative mortality of 0.5%. Choledochotomy in search of residual or recurrent common duct calculi was performed in 341 patients with a mortality of 2.1%. Detailed analysis of the causes of death in 105 patients who died during the years 1962 through 1978 revealed that cardiovascular disease, especially myocardial infarction, was the most frequent cause of death. Liver disease, most commonly cirrhosis, was also a major factor in operative mortality.