The clinical findings in 33 patients with progressive familial intrahepatic cholestasis (PFIC) are presented. Symptoms developed almost invariably before 6 months of age with severe pruritus and moderate jaundice. Other clinical findings included wheezing and nosebleeds, fat-soluble vitamin deficiency states, and cholelithiasis. Lower values for gamma-glutamyl transpeptidase, averaging 15 IU/L before the administration of phenobarbital, and cholesterol, which averaged 156 mg/dl, are helpful in distinguishing PFIC from other pediatric cholestatic liver diseases. Autosomal recessive inheritance is probable. Twenty-six patients are alive at 12.9 +/- 6.7 years of age, all having had successful surgical treatment, either partial biliary diversion (n = 17) or orthotopic liver transplantation (n = 10). Seven patients died at a mean age of 3.9 +/- 2.4 years, as a result of liver failure in two, hepatocellular carcinoma in two, and complications of liver transplantation in three.