Abstract: Objective: To study the protective effects of reduced glutathione( GSH) on the lung injury induced by N2O4 inhalation in mice.Methods: The mice lung injury model was established through exposing 64 mice to N2O4 in a 120 L sealed cabinet. Sixty- four ICR male mice were randomly divided into five groups: the control group,the N2O4 group,the low,medium and high dose GSH- treated groups,8 mice in control group,14 mice in the other groups.1.25,2.50 and 3.75 g / kg bw·d GSH were ig administered to mice in GSH- treated groups respectively for7 days before poisoning,equal volume of normal saline for control group and N2O4 group.The GSH- treated groups and the N2O4 group were exposed to N2O4 in the cabinet 1 hour after ig administration on 7 th day.The mice were killed by dislocation,and the activities of SOD and GSH- Px and the content of MDA in lung tissue were measured,and the pathology change of lung tissue was examined. Results: Compared with the control group,the SOD,GSH- Px activities and MDA content in lung tissue of N2O4 group were significantly decreased( p < 0.01).Compared with the N2O4 group,the SOD and GSH- Px activities in lung tissue of low and medium dose GSH-treated groups were significantly increased( p < 0.01),the MDA content in lung tissue of low dose GSH- treated groups was significantly increased( p < 0.01),the MDA content in lung tissue of medium dose GSH- treated groups was increased( p < 0.05).The pathology change of lung tissue showed that the injury in low dose GSH group was lighter than that in N2O4 group.Conclusion: GSH has remarkably protective effects against the lung injury induced by N2O4 inhalation in mice,and the mechanism may be related to its inhibitory effect against oxidative damage.