Ginseng, the Korean medicinal radix, has been widely used in the Chinese medicine as well as in the folk remedies for many centuries. It is claimed from experience that ginseng exerts multiple therapeutic effects in a large variety of disorders. Despite of its popularity, the chemical analysis and pharmacological study of ginseng are not firmly established. Although there are some scattered reports of ginseng effects on blood pressure, there are few reports on hypertension especially. Recently, Lee & Cho (1971) reported that the administration of ginseng significantly supresses the production of renal hypertension. This study was undertaken to reevaluate the effect of ginseng on renal hypertension and to determine whether ginseng also supresses on neurogenic hypertension, and to clarify the mechanism of this antihypertensive effect. Male rats, weighing around 180 gm on an average were used. Renal hypertension was induced by Grollman s method under general anesthesia with 35mg/kg of pentobarbital sodium. Ginseng effect on blood pressure was observed on normal, renal hypertensive and neurogenic hypertensive rats respectively. Ginseng alcohol extract (40mg/kg) was administered daily subcutaneously from 3 days prior to producing hypertension. And in renal hypertensive rats, the effects of histamine and Avil on blood pressure were also observed. Histamine (0.05mg/kg) and Avil (0.025mg/kg) were also administered daily I.M. from 3 days prior to kidney-8-ligature. The results of the experiments are as follows: 1) No significant difference was observed in blood pressure between the normotensive control and ginseng-treated normotensive rats. 2) In renal hypertensive control, the mean blood pressure already was significantly elevated on 15th day and gradually elevated. The administration of ginseng significantly supresses the production of renal hypertension from 30th day as compared with control rats. 3) The mean blood pressure in neurogenic hypertensive control was average 143.1 mmHg on 7th day. On the other hand, in ginseng treated-neurogenic hypertensive rats, the mean blood pressure was average 125.5mmHg. The administration of ginseng significantly supresses the production of neurogenic hypertension as compared with control rats. 4) In renal hypertensive rats, the administration of histamine and Avil did not differ with control rats. 5) In ginseng-treated renal hypertensive rats, cholesterol contents of plasma, adrenal, kidney and spleen were slightly decreased.