There are various congenital anomalies of the biliary system, but an ectopic opening of the common bile duct into the duodenal bulb is an extremely rare finding. Despite the recent improvement in the diagnosis and management of pancreatobiliary lesions, the general lack of knowledge and understanding about these variations is undoubtedly responsible for many of the problems that occur during the medical and surgical management of these lesions. We report here on a case of a 65-year-old man who had an ectopic opening of the common bile duct into the duodenal bulb, and this cause acute cholangitis with bile duct sludge, and also recurrent duodenal ulcer. In this case, we used abdomen CT, MRCP, duodenoscopy, EUS and ERCP for making the diagnosis. The cholangitis and duodenal ulcer was improved with medical therapy, and the patient was discharged without any surgical procedure. We report here on this unusual case and we include a review of the relevant medical literature. (Korean J Gastrointest Endosc 2008;37:459-463)