Fifteen children under the age of 15 were identified to have congenital dilatation of the biliary tree. Thirteen of them (87%) had dilatation of both intrahepatic and extrahepatic bile ducts, while two had extrahepatic biliary dilatation only. Visualization of both intrahepatic and extrahepatic biliary tree in small children before operation is possible by ultrasonography, endoscopic retrograde cholangio-pancreatography, or percutaneous transhepatic cholangiography. The advantage and disadvantage of those methods of examinations in children are discussed here. Dilatation of intrahepatic bile ducts is common in children with extrahepatic biliary dilatation. Assessment of both the intrahepatic and extrahepatic bile ducts bears a crucial role in the management of congenital biliary dilatation at operation and during the postoperative follow-up. Rouxen-Y hepaticojejunostomy with hepaticocutaneous arm was performed in our patients with satisfactory results. Residual intrahepatic stones could be removed through the hepaticocutaneous arm by choledochoscopy.