【Abstract】 Objective To investigate the effects of EPO on EBA expression and BBB permeability after ischemia reperfusion injury in rat.Methods 20 male SD rats were randomly divided into EPO treatment group、ischemia reperfusion group .The model of focal cerebral ischemia reperfusion injury was established by occluding middle cerebral artery(MCA) for 2h and reperfusing for 24h.EPO treatment group received rHu-EPO at 3000U/Kg of bodyweight,while ischemia reperfusion group received the same dose of normal saline,just before the beginning of reperfusion. The rat prefrontal cortex was removed 24h after reperfusion. the expression of EBA and fibrinogen were observed using immunohistology.Results By IHC method,the number of EBA positive microvessels was 10.60±0.93 in EPO treatment group,5.30±1.24 in ischemia reperfusion group. the number of EBA was significantly increased in EPO treatment group compared with those in ischemia reperfusion group(P<0.01);The expression of fibrinogen was 5.50±2.56 in EPO treatment group,8.60±3.12 in ischemia reperfusion group. the number of fibrinogen was significantly decreased in EPO treatment group compared with those in ischemia reperfusion group (P<0.01).Conclusions EPO treatment could increase EBA expression and reduce fibrinogen expression after ischemia reperfusion injury.EPO may exert BBB protective effect through enhancing the content of EBA ,inhibiting BBB permeability.