The diagnosis of congenital diverticulum of the gallbladder has been reported to be one of the most rare cogenital anomalies of the gallbladder. In our hospital we have the opportunity to make this diagnosis by ERCP, and simultaneously the pancreatic cyst communicating with the main pancreatic duct was also found. The patient, a 48 years old woman, came to the hospital complaining of fever and pain in the right hypochondrium. The symptom was suspected to be related to the presence of the diverticulum and cholecystectomy was performed. The gallbladder showed no particular inflammation except for fibrous adhesion between the gallbladder neck and the duodenum. The diverticulum was lying on the upper surface of the body and was shown to be true one from the histological pattern. Embryologically, this congenital diverticulum was thought to have its origin from an incomplete resolution of the solid stage and some relation between the diverticulum and the pancreatic cyst in their embryologic development was suspected.
