Twenty-three dairy calves underwent heart-lung allotransplantation after donor organs were procured using either donor core-cooling through cardiopulmonary bypass (CPB) or pulmonary artery flush (PAF) to assess which method provides optimal graft preservation. In Groups 1 (control) and 2, donors were cooled to 15 degrees C on CPB and organs were either immediately transplanted (Group 1) or stored in saline solution (4 degrees C) for 4 hours (Group 2) prior to transplantation. In Group 3, donors were pretreated with prostaglandin E1 prior to PAF with modified Euro-Collins solution. Organs were stored in saline solution (4 degrees C) for 4 hours and were then transplanted. Acute cardiopulmonary function following transplantation was assessed by the ratio of end-systolic pressure to end-systolic dimension, extravascular lung water (EVLW), lung compliance, arterial oxygenation, and lung biopsy. Cardiac function after the transplantation procedure was similar in all groups, but EVLW values and lung biopsy scores were worse after PAF. Arterial O2 tension appeared lower after PAF, but not significantly so. Core-cooling provides superior static preservation and thus improved graft function in the acute bovine model.