Duodenal diverticula are by far most commonly located along the medial wall of the second or third part of the duodenum. They are usually asymptomatic. Rarely they can cause compression on the intrapancreatic part of common bile duct with resultant upstream dilatation of the extra- and intrahepatic bile ducts; known as "Lemmel syndrome". However, in this case, the ampullary obstruction is caused by a small stone with moderate intrahepatic biliary radical dilatation as well as the common bile duct. Diverticula located at the ampulla of Vater may cause difficulty to cannulate the biliary system during endoscopy.