THE SULFOBROMOPHTHALEIN (Bromsulphalein) (BSP) retention test is generally regarded as one of the most widely used clinical measures of liver function. Owing to its time-proven value, the significance of the more important factors affecting the rate of disappearance from the blood have been studied extensively. 1 These major factors are (1) the hepatic blood flow, (2) the hepatocellular extraction, (3) conjugation, (4) biliary excretion, and (5) the urinary excretion. The importance of the latter was recognized by Rosenthal 2 when he proposed this test for clinical use. Recently, Winkler 3 reported that the urinary output of BSP is quite variable and might substantially affect the calculations of hepatic dye uptake. When a large scale metabolic study of alcoholic cirrhosis was planned in our laboratory, therefore, the design of the studies of dye clearance, using BSP and indocyanine green, included checking the urinary output. 4 We noted immediately, in our