In 47 donor organ procedures for heart-lung transplantations, lungs were preserved by autoperfusion in 21 cases and by Euro-Collins solution flush in 26 cases. Criteria used to diagnose inadequate allograft function included radiographic interstitial and alveolar infiltrates and an alveolar-arterial oxygen gradient significantly greater than 100 mm Hg at 24 hours after surgery. Oxygen gradients were calculated intraoperatively, on arrival in the intensive care unit, and during the first 24 hours after surgery. With these criteria, 15 patients with perioperative preservation damage were identified. They were compared with 32 patients without evidence of preservation injury. Patients with preservation injury showed persistently elevated alveolar-arterial oxygen gradients that were significantly above noninjury values at all times (p less than 0.03). There was no difference in donor organ ex vivo time between the two groups (227.8 +/- 74.4 vs 169.5 +/- 76.9, p = NS). The incidence of perioperative preservation injury was significantly greater among patients in the Euro-Collins solution group (12/26) than in patients with autoperfusion (3/21) (p = 0.04, Fisher's exact test). Three of the 15 recipients died of primary lung graft failure. In our hands, preservation by use of a modified Euro-Collins solution flush technique has led to unpredictable results in lung transplantation.