Six medicinal plants described in Dong-Ee-Bo-Gam as to be useful for hypertension treatment were evaluated their antihypertensive activity against Okamoto-SHR, an animal model of spontaneous hypertension. Ethanol extracts of plant samples were prepared and were p.o. administered once daily for 20 days. Average blood pressures of rats were measured during two weeks periods before drug administration. Then blood pressure of each rat was measured every three days during drug administration period. As a positive control, propranolol, ${eta}-blocker$ was used and the blood pressures of test group rats were compared with those of negative and positive control group rats. Among 6 plant extracts, Acanthopanax sessiliflorum and Atractylodes japonica (alba) extracts appeared to exhibit antihypertensive activity.