Twenty-two cases of internal biliary fistula observed between the years 1944 and 1961 are reviewed. Two were artificial fistulas. Of the 20 spontaneous fistulas, only 3 were diagnosed before operation. The signs and symptoms suggest cholecystitis. Recurring colicky pain suddenly relieved or recurrent symptoms of cholecystitis followed by diarrhea, lower abdominal pain, vomiting, and fever should suggest spontaneous internal biliary fistula. The most important roentgenographic finding is air in the biliary tree. This, with intestinal obstruction and a stone shadow in the abdomen, makes the diagnosis certain. Much depends on careful interpretation of roentgenograms and on the alertness of the diagnostician for this particular condition.