Objective To investigate the effect of histamine ( HA ) on cardiovascular system through injection into intracerebroventricular (icv) and to explore its mechanism.Methods Observing the alteration of blood pressure and heart rate bef ore and after icv HA in rabbits anaesthetized with urethane, immobilized and ass i sted by artificial respiration.Results Adiministration HA (50 μg) in to ventricule could increased blood pressure and decreased heart rate. Pretreat ment with H_1 receptor blocker, chlorpheniramine, of α_1 receptor blocker, p razosin into ventricule or intravenous injection of phentolamine or hexamethoniu m could block the central pressor response to HA. The effect of HA was not disap peared by pretreatment with H_2 receptor blocker, cimitidine or α_2 receptor b locker, yohimbine into ventricule. The bradycardic response of HA was disappeare d after bilateral cervial vagotomy.Conclusion The blood pressure to HA was mediated by central H_1 rece ptor which involved in sympathetic nervous system, while heart rate response was mediated by vagus nerve. The α_1 adrenergic receptor is also involved in the central HA pressor response.