Objective:To investigate the protective effect of free radical scavenger edaravone on adult rabbit lung ischemia-reperfusion injury in situ and the possible mechanisms. Methods:Twenty-Seven healthy New Zealand White adult rabbits were subjected to sham operation(n=6),IR(n=10),or edaravone plus IR(n=11). Ischemia-reperfusion was induced by clamping the left pulmonary hilum for 60 minutes and then removal of the clamp for another 60 minutes. Edaravone(3 mg/kg,intravenous) was given before and after ischemia. The activity of superoxide dismutase (SOD),glutathione peroxidase (GSH-PX),catalase (CAT),total anti-oxidation capability (T-AOC) and inhibiting hydroxy radical capability (IHR) in lung tissues,content of malondialdehyde(MDA) and myleoperoxidase (MPO),wet to dry ratio of lung tissue weight (W/D) were measured respectively,and lung tissues were prepared for light microscopic evaluation. Results:Compared with IR group,edaravone treatment markedly enhanced the activity of SOD,GSH-PX,CAT and T-AOC,while the MDA,MPO,W/D values were significantly reduced(P < 0.05). Pathologic evaluation showed alveoli injury,hemorrhage,white blood cell infiltration and interstitial edema in group IR were obvious,while which were lessen markedly in group with edaravone treatment. Conclusion:Treatment with edaravone can attenuate ischemia-reperfusion injury in adult rabbit lung in vivo. The protective mechanism might be mediated by its free radical scavenging and antioxidant action.