Background The composition of the lung preservation solution used in lung graft procurement has been considered the key to minimize lung injury during the period of ischemia. Low-potassium dextran glucose (LPDG), an extracellular-type solution, has been adopted by most lung transplantation centers, due to the experimental and clinical evidences that LPDG is superior to intracellular-type solutions. Ulinastatin has been shown to attenuate ischemia-reperfusion (I/R) injury in various organs in animals. We supposed that the addition of ulinastatin to LPDG as a flushing solution, would further ameliorate I/R lung injury than LPDG solution alone.Methods Twelve male New Zealand white rabbits were randomly divided into 2 groups. Using an altative in situ lung I/R model, the left lung in the control group was supplied and preserved with LPDG solution for 120 minutes. In the study group 50 000 U/kg of ulinastatin was added to the LPDG solution for lung preservation. Then re-ventilation and reperfusion of the left lung were performed for 90 minutes. Blood gas analysis (PaO2, PaCO2), mean pulmonary artery pressure (MPAP) and serum TNF-α level were measured intermittently. The pulmonary water index (D/W), tissue myeloperoxidase (MPO) activity, tissue malondialdehyde (MDA) content and morphologic changes were analyzed.Results The study group showed significantly higher PaO2 and lower MPAP at the end of reperfusion. Serum TNF-α level, left lung tissue MPO and MDA in the study group were significantly lower than those in the control group. D/W and pathologic evaluation were also remarkably different between the two groups.Conclusions This study indicated that better lung preservation could be achieved with the use of an ulinastatin modified LPDG solution. Ulinastatin further attenuated lung I/R injury, at least partly by reducing oxidative reactions,inhibiting the release of inflammatory factors and neutrophils immigration.