Many patients are, perhaps inappropriately, denied the benefits of autologous blood transfusion, because they are thought to be too ill to donate blood safely. The safety and efficacy of autologous blood donation by selected patients with end-stage heart or lung disease who are awaiting organ transplantation were studied to determine if even these critically ill patients could be suitable candidates for autologous blood donation. Seventy-two adults awaiting heart or lung transplantation were evaluated for autologous blood donation in a hospital-based blood collection facility. Phlebotomy was performed if the patient met the required medical eligibility protocol, and if he or she consented to participate. Units of blood were separated into packed red cells and plasma and stored in a frozen state. Of 48 heart transplant candidates, 31 (65%) were each able to donate 1 to 8 units of blood. The median number of exposures to allogeneic components was 1 for patients who donated and 7 for nondonors (p = 0.0141). Among patients who donated, 54 percent required allogeneic components, as compared to 88 percent of nondonors (p = 0.0968). Of 24 lung transplant candidates, 15 (63%) made 1 to 6 donations each. The median number of exposures to allogeneic components was 0 for donors and 2 for nondonors (p = 0.1871), but only 45 percent of donors required allogeneic components, as compared to 100 percent of nondonors (p = 0.0418). No serious complications during or following phlebotomy were observed. It is concluded that autologous blood donation by patients with end-stage heart or lung disease may be safe.(ABSTRACT TRUNCATED AT 250 WORDS)