Although acute acalculous cholecystitis (AAC) accounts for less than 10% of acute cholecystitis in the adult population, gangrene and perforation are much more frequent compared to the usual cases of acute cholecystitis (calculus cholecystitis). However, spontaneous biliary-enteric fistula is well recognized in AAC, 90% of which are cholecystoduodenal fistula (CDF) though it is an uncommon disorder. The majority of the CDF are caused by cholelithiasis. As patients are usually associated with complicated clinical illness, the diagnosis is often difficult to make and required surgery is often delayed. We have studied a rare complication of acute acalculous cholecystitis which was presented as intermittent upper gastrointestinal bleeding. Ulceration of the superficial branch of the cystic artery has been observed due to acalculous cholecystitis associated with a cholecystoduodenal fistula. We have performed a transfixing ligation of the bleeding vessel, cholecystectomy and simple closure of the CDF. We have finally made a diagnosis of early gallbladder cancer through a frozen section. There was no serious complication after the operation and the patient has achieved an uneventful recovery.