The capacity of the liver to metabolize intravenously loaded benzoic acid to hippuric acid was examined in 7 healthy adults and 18 patients with liver cirrhosis. Blood samples were withdrawn at 5 to 120 min after infusion of benzoic acid (15 mg/Kg), and then serum was obtained to determine the contents of the fatty acids by HPLC as well as to examine several pharmacokinetic parameters under a two-compartment model program. The urinary samples were collected at 60 min after the infusion. In the serum of the patient group, the maximum concentration (Cmax) and area under the concentration curve from zero time to the infinity (AUC) for benzoic acid remained in the normal range, but the mean transit time(MRT) and half-life time(T1/2) were significantly delayed. In serum of the patient group, the AUC for hippuric acid was hardly reduced but the Cmax was significantly reduced. Moreover, MRT, T1/2 and time to reach Cmax(Tmax) were significantly delayed. In urine at 60 min after the loading, benzoic acid was below the limit of detection and was recovered as hippuric acid with a recovery rate of 70% in the healthy adult group and 40% in the patient group.