The tests for urobilinogen in the urine and feces which are commonly employed in the clinical study of jaundice and of hepatic function have not met with general approval, because of the varying and indefinite results obtained. In a recent review of the literature on tests of hepatic function by Soffer1 this was in effect the conclusion reached. When one considers the varying dilution of the urine as well as the varying hourly excretion of the normal traces of urobilinogen in the urine (Bang2) and the much larger amounts present in the normal feces (Singer3), in which the concentration also is subject to wide variation, and when one considers further the daily and even hourly variations in the degree of urobilinuria in pathologic states, it is little wonder that qualitative tests, such as those of Ehrlich4 and Schlesinger,5 and roughly quantitative procedures, such as those