Ischemia reperfusion injury occurs in various diseases. The role of oxygen free radicals in IR injury of the lung has been spotlighted and many studies have been performed. In this study, we tried to prepare a stable rat lung model for IR injury, focusing on surrounding conditions as hilar stripped left lung, clamped left pulmonary artery and bronchus,and declamped after determined period was passed, and right main pulmonary aretery was clamped. Arterial blood gas analyes were performed at 1, 10, 20, 30, minutes after reperfusion. Before clamping, PaO2 was 95 to 120 mmHg in all animals. There were six groups; Group I : temperature 15o C, and 120 minutes clamping, Group II: 20 oC, and 120 minutes clamping, Group III : 25 oC, and 120 minutes clamping, Group IV : 15oC, 90 minutes clamping, Group V : 20 oC, 90 minutes clamping,Group VI: 20 oC, 75 minutes clamping. Each groups contained 10 Sprague Dayley rats. The humidity was maintained 100 % as circulation imerged isotonic Hartmann`s solution of the pleural cavity. In group IV, V, and VI, PaO2 decreased significantly in all animals immediately after reperfusion, but 43 % survived till 10 minutes after reperfusion, it was 74.0$pm$5.7, 73.3$pm$10.8,and 88.2$pm$17.7 mmHg. Pulmonary edema was observed histologically in 2/10 animals in group IV, 6/10 in group V , 3/10 in group VI, 9/10 in group I, and the other lungs showed all edema. We established a stable model by setting ischemic time,and temperature, between 75 to 90 minutes,15 to 20o C, and isotemperature Hartmann`s solution immersion of the pleural cavity.