We recently treated a patient with coexisting mucinous cystadenoma of the pancreas and bile duct carcinoma. A 67-year-old woman was admitted due to abdominal pain and jaundice. Abdominal ultrasonography, computed tomographic scans, and magnetic resonance imaging showed a tumor with cystic lesions in the pancreatic body. Endoscopic retrograde panceatocholangiography (ERCP) showed that the main pancreatic duct and common bile duct were severely compressed. We suspected mucinous cystoadenoma, cystadenocarcinoma, with bile duct carcinoma. At surgery, the tumor was diagnosed as adenocarcinoma, and we conducted pancreatoduodenectomy. Pathlogically, the cystic tumor was a mucinous cyst adenoma of the pancreas, and was not related to bile duct carcinoma.