【Abstract】Objective To explore the effect of B-cell lymphoma/leukemia-2(Bcl-2) overexpression on the expression of phosphor-extracellular signal-regulated kinase(p-ERK) in hippocampus after global cerebral ischemia/reperfusion . Methods 90 healthy male SD rats were randomly divided into sham opration group(SO group, n=30), Ischemia/reperfusion group(I/R group, n=30) and Bcl-2 overexpression group(Bcl-2 group, n=30). Global cerebral ischemia/reperfusion model was produced by 4-VO method.The neuronal morphology changes, apoptosis and the expression of p-ERK in CA1 and CA3 were respectively observed by the methods of HE staining, TUNEL staining and immunohistochemical staining. Results HE staining showed the number of neuron in CA1 of I/R group decreased at 48 h after global cerebral ischemia/reperfusion, companying with neuron disarrangement, nucleus membrane indistinction and nucleolus disappearance. The change in CA3 was slighter than that in CA1 and the change in Bcl-2 group was not obvious . TUNEL staining showed there was few apoptosis in SO group. The number of apoptosis peaked at 48h after global cerebral ischemia/reperfusion and the number of that in CA1（110±13）was much more than that in CA3（145±18）(P<0.05). While the apoptosis in Bcl-2 group was much less than that in I/R group （CA1：143±15，CA3：165±10）(P<0.05). Immunohistochemical staining showed expression of p-ERK in CA1 and CA3 was almost negative in SO group. In I/R group p-ERK expressed weakly in CA3 at 2h after global cerebral ischemia/reperfusion, peaked at 24 h, then decreased and expression in CA1（150±14） was weaker than that in CA3（125±9）(P<0.05). While expression of p-ERK in Bcl-2 group（CA1：123±13，CA3：100±10） was much stronger than that in I/R group(P<0.05). Conclusion Overexpression of Bcl-2 increased the expression of p-ERK while dramatically alleviated apoptosis. The mechanism of its antiapoptotic effect is related to ERK signal pathway.