Peripheral pulmonary stenosis with or without intracardiac disease is described in 14 patients with intrahepatic biliary dysgenesis. Cardiovascular malformations were not present among a large group of patients with extrahepatic biliary dysgenesis. This association of intrahepatic biliary dysgenesis and vascular malformations is postulated to be a specific malformation syndrome resulting most probably from intrauterine infection. The cardiovascular disease is usually mild. The liver dysfunction varies in severity, and is accompanied by a notable hyperlipoproteinemia with secondary xanthomata which can be ameliorated by long-term treatment with cholestyramine resin and/or vegetable oil supplements.