Intraductal papillary mucinous neoplasm (IPMN) of the bile duct is still rare and not yet understood despite of its increased incidence and similar clinicopathologic characteristics compared with IPMN of the pancreas. The fistula formation into other organs can occur in IPMN, especially the pancreatic type. To our knowl-edge, only two cases of IPMN of the bile duct with a choledochoduodenal fistula were reported and we have recently experienced a case of IPMN of the bile duct penetrating into two neighboring organs of the stom-ach and duodenum presenting with abdominal pain and jaundice. Endoscopy showed thick mucin extruding from two openings of the fistulas. Endoscopic suction of thick mucin using direct peroral cholangioscopy with ultra-slim endoscope through choledochoduodenal fis-tula was very difficult and ineffective because of very thick mucin and next endoscopic suction through the stent after prior insertion of biliary metal stent into cho-ledochogastric fistula also failed. Pathologic specimen obtained from the proximal portion of the choledocho-gastric fistula near left intrahepatic bile duct through the metal stent showed a low grade adenoma. The pa-tient declined the surgical treatment due to her old age and her abdominal pain with jaundice was improved af-ter percutaneous transhepatic biliary drainage with the irrigation of N-acetylcysteine three times daily for 10 d. Intraductal papillary mucinous neoplasm (IPMN) of the bile duct is still rare and not yet understood despite of its increased incidence and similar clinicopathologic characteristics compared with IPMN of the pancreas. The fistula formation into other organs can occur in IPMN, especially the pancreatic type. To our knowl-edge, only two cases of IPMN of the bile duct with a choledochoduodenal fistula were reported and we have recently experienced a case of IPMN of the bile duct penetrating into two nearby organs of the stom-ach and duodenum presenting with abdominal pain Endoscopy showed thick mucin extruding from two openings of the fistulas. Endoscopic suction of thick mucin using direct peroral cholangioscopy with ultra-slim endoscope through choledochoduodenal fis-tula was very difficult and ineffective because of very thick mucin and next endoscopic suction through the stent after prior insertion of biliary metal stent into cho-ledochogastric fistula also failed. Pathologic specimens obtained from the proximal portion of the choledocho-gastric fistula near the metal stent showed a low grade adenoma. The pa-tient declined the surgical treatment due to old age and her abdominal pain with jaundice was improved af -ter percutaneous transhepatic biliary drainage with the irrigation of N-acetylcysteine ​​three times daily for 10 d.