Intraductal papillary neoplasm associated with mucinous ductal ectasia is an uncommon cystic disease of the pancreas. This tumor is characterized by the multilocular cyst lined by mucin producing cells with variable degrees of atypia and ductal ectasia. In addition, this tumor has a favorable prognosis in contrast to other mucinous cystic tumor of the pancreas. Reports on intraductal mucin producing tumor are quite limited and most of them are found in Japanese literature. We report a case of intraductal papillary adenocarcinoma with marked dilatation of the pancreatic duct filled with mucin in a 72-year-old female patient.