Key Words: Choledochal cyst, common bile duct, duodenal diverticulum duodenal papilla. Subjects: Patients with diverticulosis. Abbreviation: ERCP=Endoscopic retrograde cholangiopancreatography, HD= hypotonic duodenography, DIC=drip infusion cholangiography, MRCP= magnetic resonance cholangiopancreatography.Abstract This is a review of common bile duct dilatation and duodenal diverticulosis.Special emphasis is given to the possible role of the minor papilla in the diverticulum in the formation of the dilatation.