To investigate the effects of genistein on Aβ25-35 induced damage in brain vascular endothelial cells.Methods Cell line of bEnd.3 was cultured for 48 h. Four groups were the following:control group, Aβ group, Gen group and Gen+Aβ group. Aβ25-35 was used to establish cell damage model. Gen was applied 2 hours prior to the addition of Aβ25-35. Cells were harvested for measurement after 24 hours. The level of 8-OHdG and GSH-Px were tested by ELISA and enzyme assay kit; the expression of Bcl-2 and Bax mRNA and protein were tested by RT-PCR and Western blot. Results Compared with control group, the level of 8-OHdG and GSH-Px in Aβ group was significantly increased and decreased respectively (P<0.05); compared with Aβ group, Gen group, Gen+Aβ group had reverse results (P<0.05).Compared with control group, the mRNA and protein expression of Bcl-2 were significantly down-regulated in Aβ group (P<0.05), while the mRNA and protein expression of Bax were significantly up-regulated in Aβ group (P<0.05). Compared with Aβ group, the mRNA and protein expression of Bcl-2 were significantly up-regulated in Gen group and Gen treatment group (P<0.05), while the mRNA and protein expression of Bax were significantly down-regulated in Gen group and Gen treatment group (P<0.05).Conclusion Gen could exert a protective effect on Aβ induced oxidative damage in brain vascular endothelial cells.