BACKGROUND: Lung transplantation is the effective and the last treatment in the end-stage lung disease. But ischemia-reperfusion injury can not be avoidable in the lung transplantation. We have tried to make a unilateral warm ischemia-reperfusion model in dogs and measured the changes of the gas exchange, the hemodynamic variables and lung water content. METHODS: Ten Korean mongrel dogs (body weight 20.5+/-0.5 kg) were intubated with double-lumen endotracheal tube and Swan-Ganz catheter was inserted into left pulmonary artery via right internal jugular vein and then horizontal thoracotomy was done to expose both lungs. The right main pulmonary artery, vein and main bronchus were clamped simultaneously at the right hilum for 90 minutes after collapse of right lung during left side one lung ventilation. After 90 minutes clamping, two lung ventilation was started after declamping and reinflation of right lung. We measured hemodynamic variables and analysed arterial and mixed venous blood gases at the time of two lung ventilation (TLV), one lung ventilation (OLV), clamping 90 minutes, post-reperfusion 30 minutes and 60 minutes. Also we measured water content of both lung with wet-dry method. RESULTS: PaO2 decreased compared to TLV (514.5+/-67.1, vs 278.5+/-168.5 mmHg) and pulmonary vascular resistance (172.7+/-65.9 vs 241.6+/-99.3 dyne.sec/cm5) and Qs/Qt(15.2+/-6.7 vs 26.8+/-10.4%) was increased after reperfusion to right lung at 60 minutes . Lung water content of right lung was significantly increased compared to left lung (85.1+/-4.1% vs. 80.3+/-0.7%). Pathologic conditions showed interstitial edema, congestion of blood vessel and infiltration of neutrophils. Alveolar pink exudate and hemorrhage is also observed. CONCLUSION: Decrease of oxygenation, increase of intrapulmonary shunt, pulmonary vascular resistance and lung water with reperfusion to right lung suggests that the right lung has ischemia-reperfusion injury causing lung edema.