The relationship between the oxidative stress and damages in rat type II lung cells exposed to cooking oil fume (COF) was studied. The cytotoxicity, DNA cross-links and DNA single strand breaks could be observed in the cells exposed to COF. The contents of MDA were increased and GSH were decreased significantly with exposure doses of COF and with time dependence. Pretreatment with antioxidant N-acetylcysteine (NAC) could reduce the toxicity of COF to the cells. The results suggested that cytotoxicity and DNA damages of rat type II lung cells induced by cooking oil fume might be related to the oxidative stress and the possible pathways might be the formation of lipid peroxides and interfering the GSH anti-oxidative systems of the cells.