Objective:To examine the protective effects of eryrthropoietin(EP) on neonatal SD rat cardiomyocytes injury induced by hypoxia/reoxygenation and explore its mechanisms involved. Methods:The cultured neonatal SD rat cardiomyocytes were divided into four groups:①hypoxia/reoxygenation group(H/R):deoxygenation for 2 h and reoxygenation for 4 h;②EP group:EP(10 U/ml) was added 1 h before deoxygenation,then deoxygenation for 2 h and reoxygenation for 4 h;③Wortmannin+EP group(W+EP group):Wortmannin(100 nmol/L), a specific phosphatidylinositol-3-kinase(PI3-K) inhibitor,was added at 30 min before EP incubation;④Control group. Cell apoptosis were measured by flow cytometry.The expression of EP receptor and p-Akt/Akt level were detected by Western blot. Results:EP significantly decreased the apoptotic index induced by hypoxia/reoxygenation and strongly increased p-AKt/Akt level. However, pretreatment with Wortmannin attenuated the cytoprotective effect of EP. Conclusion:Myocardial death and apoptosis are involved in hypoxia/reoxygenation injury,and EP can protect neonatal rat cardiomyocytes from hypoxia/reoxygenation-induced apoptosis. The protective effects are partly associated with PI-3K/AKt pathway.