Heart and lung transplantation is the only definitive treatment available for the patients with end-stage primary pulmonary arterial disease and Eisenmenger's syndrome. Paucity of donor and limited time of preservation of the lungs are the primary factors to limit its extensive use. We have been using autoperfusing heart-lung preparation (AHLP) for preservation of the heart and lungs in experimental animals. Metabolic substrate, amount of venous return, and pulmonary injury, which was histologically consistent with edema and hemorrhage, were the major factors to determine the survival of the donor organs, and appropriate countermeasures were thought to be necessary. The leukocyte count changes immediately after starting the preservation suggested that pathological changes of the lungs have already been induced in the very early period of AHLP. A-aDO2 changes and histological study showed that steroid and urinastatin effectively reduced the pulmonary injury. By using these drugs from very early phase of AHLP, using hyperalimentation solution of balanced substrate to improve metabolism, and setting the venous return to 30ml/kg/min, we succeeded in stable preservation of the heart and lungs for 12 hours.