This report examines why some patients with hepatobiliary disease develop unusually intense jaundice with concentrations of plasma bilirubin above 30 mg/100 ml. In a series of 19 such adults, 11 had alcoholicnutritional cirrhosis complicated by renal insufficiency. The other eight patients had acute viral hepatitis. Of these, four had excessive hemolysis with either sickle cell anemia or deficient activity of erythrocyte glucose-6-phosphate dehydrogenase. The cause of the unusual severity of jaundice in the other four patients with hepatitis was uncertain. These findings indicate that impaired renal function and excessive hemolysis can contribute to the occurrence of unusually severe jaundice in patients with hepatobiliary disease.