To define the long-term prognosis of children undergoing the Kasai operation for biliary atresia, a retrospective study was undertaken comprising 271 patients operated between 1968 and 1983. Twenty years after surgery, 63 (23%) were alive with their native liver. Serum bilirubin was normal in 21 of these patients, 12 also had normal serum aminotransferase and gamma-glutamyltransferase activities, all but 2 had signs of cirrhosis, 44 had signs of portal hypertension, 19 had late bacterial cholangitis, and 6 had gallstones. Seven female patients gave birth to 9 children, and 3 male patients fathered 6 children. After age 20, 2 patients died of liver failure and 14 underwent or are awaiting liver transplantation. Twenty-year survival with native liver was significantly better in children with biliary atresia restricted to the hepatic ducts or with cysts at the porta hepatis. In conclusion, in the long term, less than 18% of infants with biliary atresia who are treated with corrective surgery may avoid liver transplantation, but even these patients require assiduous lifelong care.