The measurement of disappearance rates of colloidal 198Au from blood flow in an excellent index of hepatic blood flow and of extraction efficiency of Kupffer cells. This, therefore, can be used as an ancillary examination of liver function especially in the patients with altered hemodynamics of the liver and portal system as in liver cirrhosis. The examination is very simple and can be performed without preparation of patients on an ambulatory basis. Normal values of disappearance rates were set by a control study of 172 normal subjects. Validity and reproducibility of the measurements were assessed. Increment in the amount of colloidal 198Au to be injected as made necessary by natural decay did not seem to affect the determinations of disappearance rates. The disappearance rate were foung to be significantly delayed in the patients with liver cirrhosis.