Abstract： Objective To investigate the effects of glutathione (GSH) precursor glutathione ethyl ester (GSEt) on smoke inhalation induced lung injury rats.Methods Sixty healthy male Sprague-Dawley (SD) rats were divided into groups by random digits table method,which included normal group,model group,GSEt high dose group and GSEt low dose group.Smoke inhalation induced lung injury rats model was established.GSEt treatments were given through intraperitoneal injection for 50 mg/kg or 150 mg/kg 5 minutes after the injury.Arterial blood gas analysis was monitored at 2,12 and 24 hours after injury in each group.Rats were sacrificed for lungs,and bronchoalveolar lavage fluid (BALF) was collected for analysis of GSH activity; and the activity of GSH,catalase (CAT) and glutathione reductase (GR) were detected in pulmonary tissue homogenate.The changes of pulmonary tissue pathology was observed through light microscope.Results Compared to normal group,arterial partial pressure of oxygen (PaO2) in model group were decreased significantly in each time; the activity of GSH in BALF,and the activity of GSH,CAT,GR in lung tissue were also observed decreased significantly.Compared with model group,GSEt treatment (150 mg/kg)with the PaO2 (mm Hg,1 mm Hg=0.133 kPa)advanced at 12 hours (82.9 ± 7.0 vs.63.9 ± 6.5,P＜0.05 ),the activity of GSH (mg/g) was increased at the 12 hours and 24 hours ( 12 hours:2.19 ± 0.41 vs.0.79 ± 0.21,24 hours:1.75 ±0.47 vs.0.67 ± 0.10,both P＜0.05 ) ; the activity of CAT (U/g) in GSEt low dose group (50 mg/kg) was increased at the 24 hours and the same increase was also observed in GSEt high dose group ( 150 mg/kg) at 12 hours and 24 hours (low dose group 24 hours:70.1 ± 5.5 vs.56.3 ± 5.0; high dose group 12 hours:90.9 ± 8.1 vs.67.9 ± 6.1,24 hours:94.7 ± 7.7 vs.56.3 ± 5.0,all P＜0.05 ) ; the activity of GR ( mmol/g ) in GSEt high dose group was increased at 24 hours (5.25 ± 0.77 vs.4.37 ± 0.64,P＜0.05 ).The histological abnormality of lung tissue was alleviated after application of GSEt (150 mg/kg) 12 hours later,less inflammatory cells infiltration and no punctate hemorrhage in lung tissues.Conclusion GSEt can enhance antioxidant capacity in lung tissues,it have a good protection for pulmonary injury.