Abstract: Objective To study effects of selenium and fluoride on oxidative stress and apoptosis in rat liver tissue.Methods The apoptosis,cell cycle,reactive oxygen species(ROS),reduced glutathione(GSH)content and lipid peroxidation (LPO)level in rat liver tissue were measured in the presence or absence of seleium(2mg/L)and fluoride(150mg/L).Results Fluoride enhanced apoptosis in rathepatocy tes,increased the number of cells in Sphase,increased ROS and LPO levels.Fluoride decreased the cellular GSH content.Selenium could antagonize the fluor ide-induced cytotoxicity by stabilizing the cellular GSH content,and by reducing ROS and LPO levels,respectively.Areduction of apoptosis in rathepatocytes after selenium treatment was observed.Conclusion Selenium can partially antagonism the fluo ride-induced lipid per oxidation and apoptosis in rathepatocytes.ROS participated the process of apoptosis.