The scintillation camera is employed for dynamic liver function studies with 131I labelled BSP. This technique provides a unique timed anatomic record of the rate and magnitude of excretion of labelled dye, and the study indicates it to be of significant value in the differentiation of jaundice. The subjects comprised 66 cases of various liver diseases including 5 cases of acute hepatitis, 18 cases of chronic hepatitis, 20 of livercirrhosis, 2 of fatty liver, 4 of Dubin Johnson's syndrom, 2 of Gilbert's disease, 2 of complete obstructive jaundice, 2 of incomplete obstructive jaundice and 10 of normal subjects. By assuming a three compartments model, kinetic analysis of 131I-BSP distributions in various organs were calculated based upon the disappearance curve of 131I-BSP radioactivity in the serum, time dependent curve of radioactivity over the liver and urinary excretion of 131I-BSP in attempts to clarify the kinetic distribution of 131I-BSP and the time dependent pool size of 131I-BSP in each compartment such as serum pool, liver pool and the other pool. The time dependent curves of Q1 (t) which represent the disappearance curve of 131I-BSP from the plasma being decreased more slowly in the early stage in chronic hepatitis, livercirrhosis and obstructive jaundice than in normal subjects. The time dependent size of 131I-BSP pool in the liver, rises more slowly in the cases of acute hepatitis, livercirrhosis and chronic hepatitis than those in normal subjects during initial 30min. The time showing the maximum points of the time dependent curve of Q2 (t) is prolonged in the cases of livercirrhosis and obstructive jaundice and also the valves of maximum points are decreased in liver diseases. These facts indicate that the 131I-BSP uptake into the liver is decreased in liver diseases. While the maximum point of time dependent curve of Q2 (t) decrease more markedly in livercirrhosis and acute hepatitis. The individual values for the fractional rate constant for distribution and metabolism of 131I-BSP are expressed as k01, k02, k12, k13, k21, k23, k31, and k13. In controls, the calculated rate constant of k21, expressing the uptake from the plasma to liver, is (7.08±1.32)×10-2min-1, k12 is (1.974±0.1301)×10-2min-1 and k02, expressing the excretion from liver into bile duct, is (3.994±1.10)×10-3min-1. The cases of acute hepatitis, liver cirrhosis and obstructive jaundice showed a more remarkable decrease in the values of k21 and k02 than normal subjects. In the cases of Dubin Johnson's Syndrom, remarkable decrease (P<0.01) in the values of k02 and billiary excretion of 131I-BSP is showed, but the second rising curve in time dependent curve of 131I-BSP radioactivity in serum is not demonstrated. If the ratio of blood 131IBSP value in 30min, divided by the value in 2min. after intravenous injection of 131I-BSP is calculated, the ratio appears to be of significant value in differentiation of the various type of liver diseases.