Objective To prove the protective effect of lung ischemic preconditioning on enhancing the canine lung preservation and reducing allograft lung dysfunction after transplantation.Methods Ten pairs of adult canines underwent left lung allotransplantation. Five donors were treated with ischemic preconditioning [their left hilus was clamped for 10 minutes and released for 15 minutes (Group IP)], and five donors were not treated with ischemic preconditioning (Group C). The donor lungs were flushed with 4℃ Euro-Collin's solution (ECS) and stored in the same solution for two and a half hour, then transplanted to the recipient canines, who were observed for one to two hours after transplantation. The lung venous blood of the recipient and the donor lung tissue were collected just after thoracotomy and one hour after reperfusion of the transplanted lung in both groups.Results The number of polymorphonuclear (PMN) was significantly higher in Group IP than in Group C (P<0.05). However, the number of PMN in lung interstitium under microscope was less in Group IP than in Group C. The thromboxane (TXB2), malondialdehyde (MDA) and mean pulmonary artery pressure (MPAP) contents were significantly lower in Group IP than in Group C (P<0.05). The superoxide dismutase (SOD) and the lung venous blood oxygen tension (PvO2) contents were significantly higher in Group IP than in Group C (P<0.05). Histological findings showed less damages in Group IP than in Group C.Conclusions The protective effect of ischemic preconditioning together with ECS flush and storage is superior to using ECS alone. The possible mechanisms may be that ischemic preconditioning inhibits the accumulation and activation of PMN in lung tissue and reduces the production of oxygen free radicals.