Objective To study the mechanism of toxicity of hexane. Methods SD rats inhaled 15 g/ma n-hexane statically for 8 hours. Results The levels of GSH in whole blood of rats declined significantly (t-test,P＜0. 01). The levels of MDA in serum of rats revealed increasing trend but without statistical significance (t-test,P＞0. 05). The activities of SOD and GSH-Px in liver of rats decreased significantly (t-test,P＜0.01). Conclusion n-Hexane could induce or enhance the reaction of oxygen free radical in organism,and result in damages of lipid peroxidation,which might be one of the mechanisms of the toxicity of alkane.