Infants with idiopathic perinatal fibroinflammatory obliteration of the lumen of the extrahepatic biliary tree ("biliary atresia") invariably died of biliary cirrhosis before surgical techniques were devised to permit drainage of bile into the duodenum. Survival rates in operated patients now approach 75 percent at 10 years. While definitive diagnosis of biliary atresia without the use of cholangiography at laparotomy is difficult, because other disorders have similar clinical features, early diagnosis is important. The earlier surgery is undertaken, the more successful it is. With delay, irreversible changes occur in the liver that produce portal hypertension. This and liver failure eventually make liver transplantation necessary even in some operated patients. Hepatic disease associated with biliary atresia is in part due to delay in diagnosis, but complications of surgical therapy, such as ascending cholangitis, also play a role. With prolonged survival and as numbers of liver transplant recipients rise, new therapy-related complications, such as those associated with immunosuppression, will become more important in surgically treated biliary atresia.