The incidence of congenital choledochal cysts is 1/100,000 to 1/150,000, and the most widely accepted cause is an anomalous junction of the pancreatic duct and the common bile duct. According to our intraoperative cholangiography, there is marked cystic dilation of the extrahepatic and intrahepatic bile ducts and a normal intrapancreatic bile duct. With respect to the intrahepatic ducts, surgery should be individualized depending on whether (1) both lobes are involved, (2) strictures and stones are present, (3) cirrhosis has developed, or (4) an associated malignancy is localized or metastatic.