Optimal techniques of heart-lung preservation are yet to be defined. The aim of this study was to develop, in a canine model, a method of heart-lung preservation which would permit distant procurement of the organs. The animals were divided into 2 groups. In the experimental group (N = 6) the method of preservation consisted of cold cardioplegic arrest of the heart with St. Thomas' Hospital solution containing superoxide dismutase, catalase and deferoxamine, followed by cold pulmonary artery flush with modified Euro-Collins solution to which prostaglandin E1, superoxide dismutase, catalase, deferoxamine and Dextran 40 were added. Following harvesting, the heart-lung block was stored for 8 hours in cold (4 degrees C) Euro-Collins solution containing superoxide dismutase, catalase, deferoxamine, lactobionic acid, raffinose, mannitol, Dextran 40, magnesium sulfate, insulin and penicillin. In the control group (n = 6), the heart-lung block underwent the same treatment as the experimental group except that lactobionic acid, raffinose and insulin were omitted from the storage solution, and that oxygen radical scavengers were excluded from the cardioplegic, pneumoplegic and storage solutions. Histologic and electron microscopic examinations of heart-lung specimens taken before and after 8 hours cold storage of the organs suggested that our preservation technique may be effective in preventing ischemia-induced injury.