A 50-year-old man presented with acute pancreatitis. Abdominal CT showed cystic dilatation of common bile duct and diffuse dilatation of pancreatic duct. ERCP showed pancreas divisum, choledochal cyst and pancreatic duct stones. Minor papilla sphincterotomy and insertion of nasopancreatic tube were performed for drainage of dorsal pancreatic duct. And then, he underwent Whipples operation for excision of choledochal cyst and decompresion of dorsal pancreatic duct. (Kor J Gastrointest Endosc 15: 811-816, 1995)