Objective:To observe the protective effect of methanesulfonic acid cinepazideon(CMI) on cerebral ischemia reperfusion injury in rats. Methods:The local cerebral ischemia/reperfusion model was established by intraluminal thread occlusion of the middle cerebral artery occlusion (MCAO) in rats. Seventy-two male SD rats were randomly divided into five groups:model group,sham group,CMI treatment group (20,40,80 mg/kg) and cinepazide maleate treatment group (40 mg/kg). Thrombosis,platelet aggregation,the infraction volume and pathomorphological changes of brain tissue were observed in each group. Results:Compared with model group,CMI could reduce infract volume,thrombosis and inhibit platelet aggregation (P < 0.05). Also it could reduce neurons karyopyknosis,dissolution and swelling of the brain cells. And the effects had no difference with cinepazide maleate. Conclusion:CMI has a marked neuroprotective effect on local cerebral ischemia reperfusion injury in rats.