AIM: To investigate the protective effects of exogenous estrogen and effects on expression of Bcl-2 and Bax protein against retinal ischemia-reperfusion injury(RIRI)． METHODS:Seventy-two SD rats were randomly divided into normal control(N,n=8),simple ischemia-reperfusion model group(IR, n=32),estradiol benzoate treatment group (E₂+IR,n=32).In the latter two groups,each sub-group was determined by the time after ischemia-reperfusion: 6, 24, 48 and 72 hours. By improving the anterior chamber intraocular pression to set up ischemia-reperfusion model in big rats.The morphology change of retina tissue was detected by light microscope.The changes of Bcl-2, Bax protein were measured by immunohistochemistry in retinal tissue . RESULTS:.In the E₂+IR group, the damage of the retina was significantly reduced than IR group.In IR group,the expression of Bax protein began to add at 6 hours after reperfusion,24 hours reached the peak,48 hours began to reduce,and 72 hours had weak expression. In IR group the expression of Bcl-2 reached the peak at 6 hours,with time going,the expression of Bax began to reduce;but in E2+IR group were increased significantly than IR group in all the time points(P<0.01). CONCLUSION:The retina organization was injured by ischemia-reperfusion injury.Bcl-2 and Bax protein had taken part in the RIRI. Estradiol benzoate could increase the expression of Bcl-2 and cut the expression of Bax protein, and protect the retina tissue.