The increase of nonprotein nitrogen in the presence of jaundice has received relatively little attention in the diagnosis and management of icteric patients. High values of nonprotein nitrogen in the presence of icterus are usually not appreciated in spite of the fact that reports in the literature point to the comparative frequency of renal injury secondary to hepatic disease. Elevated levels of blood urea nitrogen in liver disease were reported by Wilensky,1Meyers,2Eiss,3Schutz and his associates,4Rowntree,5Elsom,6Hoesch7and Nonnenbruch,8among others. Wilensky9found the incidence of increased urea nitrogen to be proportional to the severity of the disease and to the presence of complications. The presence of a high level of nonprotein nitrogen in Weil's disease is a well known fact. A perusal of the literature10reveals that a rise of the nonprotein nitrogen level in