Extrahepatic biliary atresia is an obliterative cholangiopathy that involves all or part of the extrahepatic biliary tree and, in many cases, the intrahepatic bile ducts. In the United States, from 400 to 600 new cases of biliary atresia are encountered annually. The diagnosis is usually suggested by the persistence of jaundice for 6 weeks or more after birth. Several factors have been considered for the pathogenesis of extrahepatic biliary atresia, including viral infection, metabolic insults, and abnormalities in bile duct morphogenesis. Although selected patients benefit from prompt diagnosis and Kasai portoenterostomy surgical intervention within the first 60 days of life, many ultimately require liver transplantation because of portal hypertension, recurrent cholangitis, and cirrhosis.