Abstract: Ebselen(2-phenyl-1,2-benzisoselenanzol-3(2H) one, C₁₃H₉NOSe) is a seleno organic anti oxidant compound. In this study, the effect of ebselen on lipid peroxidation damage induced by O^·-₂ and ·OH in vitro , of cultured rat cortical neuron and cortical mitochondria was studied. When neuron was exposed to hypoxanthine/xathine oxidase system and vitamin C/CuSO₄ system, obvious damage was dectected: lactic dehydrogenase(LDH)was released and TBARS content increased. Ebselen(10,25,50 μmol·L^-1) reduced LDH efflux induced by O^·- ₂ and ·OH in a dose dependent manner. As for the TBARS content, from 5 μmol·L^-1 to 50 μmol·L^-1, ebselen negated its increase, also dose-dependently. Furthermore, ebselen lowered TBARS content of cortical mitochondria treated with O^·- ₂ and ·OH in a dose-related manner. But ebselen showed no activity of scavenging O^·-₂ and ·OH. This suggests that ebselen has direct anti-oxidant activity on neuron and its activity is not achieved by scavenging oxygen free radical.