Single flush perfusion of the lung represents one concept of pulmonary preservation that has provided satisfactory results in both experimental and clinical situations. The technique has allowed successful distant organ procurement, with consequent enlargement of the available donor pool. Both cold modified blood (CMB) and modified Euro-Collins solution (ECS) are currently used as perfusates, although the volumes of each used clinically are different. CMB is administered at 20 ml/kg and ECS at 60 ml/kg. Both techniques combine the use of a prostaglandin to enhance preservation. In this study these two perfusion techniques were compared in a canine model of unilateral left lung allotransplantation after 6 hours of storage, with subsequent ligation of the recipient's contralateral pulmonary artery and bronchus. Equal volumes of both solutions were used (20 ml/kg) to determine whether the blood vehicle was necessary to provide good preservation at this volume. Assessment of pulmonary preservation was determined by animal survival, blood gas analyses, hemodynamic values, and measurement of lung water content. All animals survived the 24-hour experimental period in stable condition. Postoperative oxygenation was well maintained at control values throughout this period with no significant difference between groups. The pulmonary vascular resistance index was significantly higher in the CMB group at 1 hour (p < 0.05). Lung compliance, assessed by peak-inspiratory pressure, was impaired to a greater extent in the CMB group than in the ECS animals (p < 0.01 at 12 and 24 hours). Lungs preserved with CMB accumulated significantly more water by the end of the experiment than those preserved with ECS (p < 0.05). The results suggest (1) that 20 ml/kg of ECS in combination with Iloprost provides good preservation for 6 hours in the dog, and (2) that ECS may provide better preservation than CMB in this model.