With the aid of extracorporeal circulation, nine dogs underwent orthotopic cardiopulmonary transplantation after preservation of the donor heart in a hypothermic amino acid[glutamate, aspartate] enriched high potassium extracellular solution, and preservation of the donor lung with hypothermic low potassium dextran solution from June 1990 to May 1991. The mean body weights of dogs were 20kg and the recipients` preoperative hematologic and hemodynamic pictures were within normal range except slightly decreased level of albumin and total protein, which was supposed to be due to malnutrition. The following modifications of the original Stanford technique were emphasized: [1] the posterior mediastinum is dissected as little as possible with meticulous hemostasis; [2] the surgical procedure is kept away from the phrenic and vagus nerves; [3] the tracheal anastomosis may be wrapped with recipient`s pulmonary artery flap or surrouding soft tissues. A combination of Cyclosporine, Azathioprine, corticosteroid was used as perioperative immunosuppressive therapy. Postoperatively all recipients could be weaned from extracorporeal circulation, showing favorable vital signs, but within 24 hours, irreversible congetive heart failure, ascites, arrhythmias developed with a mean survival time 13.6$pm$6.6[n=9, range=6~26] hours. Hemoglobin and platelet counts were significantly[p<0.05] decreased postoperatively, which is thought to be attributed to blood damage by cardiopulmonary bypass and hemodilution. Postmortem finding included multiple subendocardial patch hemorrhage in both atrial and ventricular cavities, pulmonary and liver congestion, and all tracheal anastomoses were intact. Further consideration about quality control of the animal, infection, rejection, the effect of cardiopulmonary bypass on the experimental animal is required to improve the results.