Multiple biliary papillomatosis are extremely rare, fifty one cases have been reported in the literature. Clinical symptoms are associated with obsructive jaundice and cholangitis. Malignant transformation into adenocarcinoma had been described. We report a case of multiple papillomatosis in the entire biliary ductal system with malignant transformation, in which endoscopic retrograde cholangiopancreatography and peroral choledochoscopy showed multiple polypoid lesicons. The endoscopic sphincterotomy and the intraductal biopsy confirmed the histologic diagnosis of multiple papillomatosis and adenocarcinoma. (Korean J Gastrointest Endosc 18: 625-629, 1998)