In this study the effect of alcohol extract of atractlis (AAE) on the blood pressure of the rabbit was investigated. The results of the experiment are as follows. AAE elicited hypotension with doses ranging from 3 to 30 mg/kg, i.v., exhibiting a linear dose-relationship. This effect of AAE was abolished by atropine and potentiated by physostigmine, while not affected by diphenhydramine, hexamethonium, propranolol and cyproheptadine. AAE did not influence the pressor responses to norepinephrine and the depressor to isoproterenol. The above results indicate that AAE produced the hypotension by stimulating the parasympathetic nervous system related to acetylcholine.