Intravenous injection of Mori Radicis Cortex Water Extract (MWE) regularly caused the does-related, lowering of blood pressure in the rabbits anesthetized with urethane, and then did not show the cumulative effect and the tachyphylaxis. The hypotensive effects of MWE were inhibited by atropine, chlorisodamine, phentolamine and bethanidine, while not altered by diphenhydramine, propranolol and cyproheptadine. Atropine after chlorisondamine did not alter the effect of MWE. MWE potentiated the pressor effect of nore-pinephrine, but did not carotid occlusion was inhibited by previous administration of MWE. It is conclude that MWE elicits hypotensive action in the rabbit by the centrally induced cholinergic effect and the inhibitation of responses to sypathetic adrenergic nerve activation.