Influence of Eucommiae Cortex in Korea on the blood pressure of the rabbit was examined, 1) The intravenous injection of 3 mg/kg, 10 mg/kg and 30 mg/kg of the water extract to the rabbit decreased its blood pressure to $9.7;{pm};1.9,;26.4;{pm};1.7;and ;35.5;{pm};2.7;mmHg$. respectively. 2) The intravenous injection of 10 mg/kg of the water extract did not show any remarkable influence to the blood pressure caused by the intravenous injection of acetylcholine $10^{-8};g/kg; and ;10^{-7};g/kg$. 3) The intravenous injection of the water extract after the intravenous injection atropine 2mg/kg did not show any remarkable change to the blood pressure 4) The intravenous injection of the water extract after the intravenous injection of propranolol 2mg/kg slightly decreased the blood pressure.