The authors adopted the model of rat heart heterotopic transplantation established by Ono who anastomosed the donor ascending aorta and pulmonary artery to the recipient abdominal aorta and inferior vena cava respectively, and sonie improvemenLs on this model were made in this experimenL The time of procedure and the ischemic time of the donor heart were shortened, and the protection of the donor heart was satisfactory. The successful rate of 52 formal transplantations was 88%. The main reason of surgical failure is bleeding from the anastomosis. To lessen the intraoperative bleeding is a key factor to make the procedure successful. The method of the improved experimental model and the expenence are described in details.