This study was designed to investigate the function of 17ÃŸ-estradiol (17ÃŸ-E2) against oxidative stress on the cell death of mice bone marrow mesenchymal stem cells (BMSCs) induced by hydrogen peroxide (H2O2). BMSCs were treated with 17ÃŸ-E2 for 24 h and then treated with 100 'M H2O2 for 1 h. Cell viability, apoptosis, caspase-9 mRNA, JNKs (Jun N-terminal kinases) and c-Jun protein expression in BMSCs were evaluated. Cell apoptosis of BMSCs were increased in a dose-dependent manner after treated with H2O2 compared to control group. But pretreatment with 17ÃŸ-E2 can inhibit apoptosis of BMSCs, preserve the mitochondrial transmembrane potential, decrease caspase-9 mRNA, JNK1/2 and c-Jun protein expression. In conclusion, 17ÃŸ-E2 exerts antiapoptotic effects in BMSCs which related to the mitochondria death pathway and JNKs pathway. The study revealed that 17ÃŸ-E2 can reduce the donor stem cells damage.