To evaluate the diagnostic significance of the blood disappearance rate of 198Au-colloid and to evaluate the change of hepatic blood flow during position change from supine to erect, we measured the half time of blood disappearance rate of 198Au-colloid using external counting method in 94 normal persons and in 77 patients with various hepatic diseases. The results obtained were as follows: 1) In normal control, the mean blood disappearance half time of 198Au-colloid in supine position was 2.7¡¾0.4 minutes. There was no significant difference of hepatic blood flow in age and sex. 2) In acute hepatitis, chronic hepatitis and hepatic cirrhosis, the mean blood disappearance half times in supine position were 3.0¡¾0.45, 3.5¡¾0.74, 7.2¡¾3.6 minutes respectively. The hepatic blood flow of the patients with chronic hepatitis and hepatic cirrhosis were significantly decreased than that of normal control. 3) In the normal control and acute hepatitis, the decreaces of the hepatic blood flow during the position change from supine to erect were 27.7% and 22.6% respectively.