The influence of cimetidine treatment(100 ㎎/㎏, single i.p.) on the pharmacokinetic parameters of indocyanine green(ICG) in the rat was investigated in order to estimate the decreasing effect of the hepatic blood flow with cimetidine on the hepatic clearance of ICG on the basis of hepatic perfusion-limited model. ICG (1 ㎎/㎏) was respectively administered via femoral and portal vein to the control and to the cimetidine-treated rats. The rate constant (K_(12), K_(20)) and the systemic clearance(CL_t) of ICG were significantly(p < 0.05) decreased regardless of the route of administration in the cimetidine-treated rats, but no significant differences were observed in hematocrit and liver weight. The biliary excretion rates of ICG were also decreased regardless of the route of administration in the cimetidine-treated rats. It may be concluded that the decreased hepatic blood flow with cimetidine mainly contributed to the decreased hepatic uptake and the decreased systemic clearance of ICG.