Excessive taking fluoride (F) causes severe damage to reproductive system through stimulation of apoptosis and oxidant stress. Selenium (Se) may promote anti-oxidant enzymes and invert cell apoptosis. The aim of this study was to investigate the effect of Se on peripheral blood mononuclear cell (PBMC) apoptosis and oxidant stress in women with fluorosis. Sixty women were divided into three groups according to serum and urine fluoride and hair Se as High F + high Se group, High F group and Control group. The activities of anti-oxidant enzymes, malondialdehyde (MDA) and Se were measured. The levels of sirtuin type 1 (SIRT1), estradiol (E 2), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were measured by enzyme-linked immune sorbent assay (ELISA) kits. The expression of protein and apoptosis rate were detected by Western blot and Flow cytometry. The levels of E 2 , anti-oxidant enzymes in High F group were significantly lower than that in Control group, while the levels of SIRT1 and MDA were significantly higher. The levels of anti-oxidant enzymes and heat shock protein 70 (HSP70) were significantly increased in High Se + high F group while the expression of caspase-3 was significantly increased in high F group. The levels of LH and FSH in serum were significantly increased in High F group and High Se + high F group. Therefore, Se alleviates apoptosis induced by F through improving the expression of HSP70 and reduces oxidative stress by regulating levels of SIRT1 and anti-oxidant enzymes, and the secretion of certain reproductive hormones. [ABSTRACT FROM AUTHOR]