The success of treating patients with biliary atresia is related to the remaining liver function. The latter is related to age. Therefore, early diagnosis is important; even 2-week-old babies with jaundice should be screened. If screening indicates the possibility of biliary atresia, the only way to conclusively exclude biliary atresia is cholangiography. Endoscopic retrograde cholangiopancreatography is being more frequently utilized to successfully outline the biliary tree in these young patients. The Kasai procedure has a 5-year success rate of about 30%. This success rate may be increased by utilizing an antireflux valve fashioned from the enteric limb to prevent a persistent incidence of reflux cholangitis. Biliary atresia may arise from environmental insults (cytomegalovirus), or more uncommonly congenital defects (anomalous pancreaticobiliary union). Extrahepatic biliary cysts are more common than the intrahepatic variety. The former are associated with anomalous pancreaticobiliary unions and cholangiocarcinoma. These associations support the mechanism of pancreatic juice reflux into the biliary tree. Therefore, excision of the cyst is the treatment of choice. Caroli's disease (intrahepatic biliary cysts) may be diagnosed by observing intracystic vascular dots (Marchal's sign), utilizing ultrasound or computed tomography.