Abstract: Berbamine hydrochloride is an alkaloid isolated from Berberis poiretii. The experiments reported here were designed to observe the hypotensive action and mechanism of Berbamine hydrochloride in cats, doga and rabbits, using many models such as intravenous administration, intravertebral arterial administration, in pithed cat, the superior ganglion-nictating membrane preparation in cat, the heart in situ, and the perfused vessel in rat's lower limb. The following results were obtained:Berbamine hydrochloride reduced blood pressure in various animals. The blood pressure was reduced about 20% by giving 5 mg/kg of Berbamine hydrochloride intravenously. As the dose increased to 10 mg/kg (i.v.), the reduction of blood pressure was overIn normal cats, blood pressure was reduced significantly and immediately after vertebral arterial administion. Berbamine hydrochloride 0.5mg increased the fluid flow in perfused rat lower limb.Berbamine hydrochloride showed no superior dervical ganglionic blockade and did not show any antagonism to adrenaline and atropine.These results showed that the hypotensive activity of Berbamine hydrochloride was based on its action on central nervous system and dilatation of blood vessels.