Cholestasis associated with Alagille syndrome may, in a few cases, be extremely severe and result in major impairment in the quality of life during early childhood and end up in cirrhosis eventually. We report the results of liver transplantation in 12 children with a severe hepatic form of Alagille syndrome. All children presented with cholestatic jaundice from birth, peculiar facies, stenosis of the peripheral pulmonary artery, and posterior embryotoxon; butterfly-like vertebrae were present in 9 children. At the time of transplantation (mean age 7 years 10 months) refractory pruritus was present in 9 children, xanthoma in 11, and height and weight retardation in 11. Total serum bilirubin ranged from 116 to 322 mumol/L and total serum cholesterol from 3.5 to 29 mmol/L. Systolic right ventricular pressure was moderately raised (36 to 48 mmHg) in 5 children; mean creatinine clearance was 99 ml/min/1.73 m2. Histologic examination of the removed livers showed cirrhosis, severe annular fibrosis, and moderate portal fibrosis in 4 children each. Follow-up in the 11 survivors has ranged from 14 months to 5 1/2 years. All lead normal lives. Pruritus and xanthomas disappeared. Increase in height was observed in 8 of the 10 survivors who had growth retardation prior to transplantation. School level is normal in 4 (median age at LT: 5 yr 9 mo) and below normal in 6 (median age at OLT: 9 yr 9 mo). Liver function tests are normal in 10 children. Mean creatinine clearance is 101 ml/min/1.73 m2. These results indicate that the quality of life can be considerably improved after liver transplantation in children with a severe hepatic form of Alagille syndrome and suggest that it could be carried out before these children attend elementary school.