Congenital biliary tract disease. Jaundice in the pediatric patient requires prompt and directed evaluation. This dictum is highlighted in infants with biliary atresia, in whom the progressive sclerosing process results in complete obliteration of patent but microscopic hilar biliary structures by 4 months of age. Kasai's operation, if done before that time, will re-establish bile drainage in 90% of infants. One fourth to one third of patients achieve long-term jaundice-free survival. Complications of cholangitis, portal hypertension, and fat malabsorption are experienced by many patients. In children with early or late operative failure, liver replacement now offers legitimate hope for extended survival. Choledochal cyst is a conglomerate of pancreaticobiliary anomalies consisting of a choledochal cyst, a common-channel-type pancreaticobiliary junction, intrahepatic cystic disease, and partial obstruction of the distal common bile duct. Many patients have one or more of these malformations. It is now widely accepted that the preferred treatment of choledochal cyst is total excision of the diseased biliary duct with reconstruction by Roux-en-Y choledochojejunostomy. "Internal" excision avoids injury to other structures in the hepatoduodenal ligament, particularly if pericystic inflammation is present. Congenital perforation of the common bile duct responds in most cases to simple peritoneal drainage of the perforation. Retention of the tube cholecystostomy is useful for subsequent cholangiographic follow-up. Tube cholecystostomy may also be useful for irrigation of the biliary tract in infants with inspissated bile syndrome. 