Fifty four infants with hepatobiliary disease and conjugated hyperbilirubinaemia of more than two weeks' duration were identified in a defined area of south east England in a prospective study between January 1971 and December 1973. The overall incidence was one case per 2500 live births. The cases were regularly reviewed and all survivors except one were assessed at age 10 years. Nine of 11 with extrahepatic biliary atresia died from liver disease by 2 years of age, one died at 5 years, and the survivor has cirrhosis with portal hypertension. Four out of seven with alpha 1 antitrypsin deficiency died aged 1 to 3 years from liver disease and one of the survivors has cirrhosis. All three infants with intrauterine infection and one with chromosomal abnormality died in infancy. Three children with other associated factors, choledochal cyst, galactosaemia, and rhesus isoimmunisation, recovered completely with no persisting liver disease. Two of 29 with cryptogenic hepatitis died, but only a further two have signs of persisting liver disease. Perinatal complications were more common in this group. Four of the 27 children surviving to the age of 10 years are educationally subnormal. Prognosis for infants with intrahepatic liver disease in the absence of known associated factors is good and every effort should be made to minimise the short term effects of cholestasis.