This study was carried out for the purpose of observing the effect of Korean Acanthopanax Radicis Cortex on renal hypertension and to clarify the mechanism of this effect, making use of its ethanol extract. Adult male or female rats, weighing 180-250g, were divided into 3 groups; the first for normotensive control, the second for hypertensive control and the third for hypertensive Acantopanax-treatment. Rats in the normotensive and hypertensive control group were administered 0.9% saline subcutaneously only, whereas those in the Acanthopanax-treated hypertensive group were administered 50mg/kg Acanthopanax ethanol extract subcutanously once a day. Changes of original blood pressure, and responses of blood pressure to various agents(norepinephrine, angiotensin, acetylcholine, serotonin and histamine) were recorded for each group on the initial, 18th, 32nd and 46th days of the experiment. The results obtained in this experiment are as follows: 1) The initial blood pressure was 102.6±7.6㎜Hg on the average. The blood pressures of the normotensive control group were not observed to alter significantly at any period in the course of the experiment. 2) The mean blood pressures in the hypertensive control group were recorded at 120.3±10.4㎜Hg on the 18th day, at 134.5±9.2 on the 32nd day and at 138.8±8.3 on the 46th day, thus revealing significant elevation in comparison with the corresponding normotensive control group blood pressures. On the other hand, the mean blood pressures in Acanthopanax-treated hypertensive group on the 18th, 32nd and 46th days were 118.3±9.7, 129.9±8.3 and 120.2±8.3㎜Hg respectively. The blood pressures of the hypertensive-Acanthopanax group recorded on the 46th day revealed a significant difference as compared with those of the corresponding hypertensive control group. 3) On the 46th day of this experiment, the responses of blood pressure to acetylcholine in the hypertensive-Acanthopanax group were suppressed significantly as compared with those of the hypertensive control group, and in the latter group, angiotensin was decreased markedly as compared with the corresponding normotensive control group. In contrast, pressor action of norepinephrine and depressor action of serotonin and histamine did not differ significantly among the three groups. These results suggest that Acanthopanax ethanol extract suppresses the induction of renal hypertension by means of a cholinergic action such as that caused by acetylcholine.