The prognosis of 97 patients with congenital biliary atresia treated by hepatic portoenterostomy was studied. In 37 of 97 patients (38%), good bile excretion was observed after surgery, and jaundice cleared. Sixteen of the 37 patients developed ascending cholangitis; 11, esophageal varices; and nine died. Seven died of ascending cholangitis and two of hepatic failure. Fourteen patients had an uneventful course. In the remaining 60 patients, bile excretion was scanty, and the disease progressed to biliary cirrhosis; 52 died. Causes of death were hepatic failure (53%), intracranial hemorrhage (16%), rupture of esophageal varices (12%), severe dehydration (9%), and postoperative complications (9%). The age at death ranged from 2 to 52 months, with an average at 16 months.