Biliary cystadenoma is a rare biliary ductal neoplasm that usually arises in the liver and less frequently in the extrahepatic bile ducts. Clinical manifestations are non-specific; hence preoperative diagnosis depends heavily on imaging. Computed tomography, ultrasonography, angiography and cholangiogram are useful diagnostic procedures in biliary cystic tumor, but definite diagnosis depends on histologic diagnosis. Surgical resection often yields excellent results. Surgical procedures used to treat cystadenomas include: aspiration, drainage, marsupialization, and excision. If there is no evidence of metastasis, complete resection of these tumors is necessary for a complete cure. We experienced an 80-year-old man who complained of jaundice and RUQ pain. He was diagnosed as biliary mucinous cystadenoma, We confirmed our diagnosis by cholangioscopic biopsy, and performed endoscopic sphincterotomy(EST). So, we report this case and have reviewed the relevant literature as a part of our report for the subject case. (Korean J Gastrointest Endosc 17: 85-90, 1997)