Heart-lung transplantation has been limited to on-site organ procurement because current methods of lung preservation are unreliable for periods in excess of one hour. A method of dynamic heart-lung preservation has been evaluated as a possible means for distant procurement for human transplantation. Canine and bovine heart-lung blocks were removed and preserved by autoperfusion for periods of two to nine hours. The key features of the method included normothermic coronary autoperfusion with donor blood by an autoregulating beating heart, and a stabilizing reservoir bag interposed between the donor aorta and the right atrium. The reservoir is positioned one meter above the aortic valve, and determines the pressure in the aorta. Flow from the bag to the right heart dictates venous return, pulmonary blood flow, and ventricular stroke volume. The lungs are ventilated with room air and 5% to 10% of CO2, at 4 liters/minute. Normothermia is ensured by immersion of the heart-lungs block in a temperature controlled crystalloid bath. Eleven canine and eight bovine heart-lung blocks were evaluated for two to nine hours. Lung function was excellent during this period, and cardiac output did not decline from pre-harvest levels. Five heart-lung allografts were transplanted after an average of four hours of autoperfusion and all functioned satisfactorily. All animals could be weaned from the extracorporeal circulation support. Two to three hours later, cardiac outputs and arterial pO2 were normal. The peak airway pressures averaged 29 cm H2O.(ABSTRACT TRUNCATED AT 250 WORDS)