Improved techniques of pulmonary preservation would help alleviate the critical shortage of donor organs in lung transplantation and would improve early graft function. A previous study demonstrated that cold pulmonary artery flush with low-potassium dextran solution was superior to Euro-Collins solution in preservation of canine lung allografts stored for 12 hours when no pulmonary vasodilator was used before donor lung flush. The present study was designed to determine whether donor pretreatment with prostaglandin E1 would affect the superiority of low-potassium dextran as a preservation solution. Prostaglandin E1 was infused (50 μg/min) in 12 donor dogs until potent vasodilatation was demonstrated. Low-pressure pulmonary artery flush (50 ml/kg) with either Euro-Collins or low-potassium dextran solution (n = 6 for each group) was performed at 4° C in a randomized, blinded fashion. Heart-lung blocks were extracted and stored at 4° C for 18 hours before left lung allografting. Inflatable cuffs were placed around each pulmonary artery, allowing independent study of the native and transplanted lungs. All 12 recipient dogs survived the 3-day assessment period. Lungs flushed and stored in Euro-Collins or low-potassium dextran solution provided equivalent gas exchange function on day 0 (arterial oxygen tension: Euro-Collins 289 ± 105 mm Hg versus low-potassium dextran 265 ± 111 mm Hg; mean ± standard error of the mean) and on day 3 (Euro-Collins 516 ± 45 mm Hg versus low-potassium dextran 354 ± 77 mm Hg; p = 0.10). Mean pulmonary artery pressures in the transplanted lung were not significantly different in the Euro-Collins and low-potassium dextran groups on day 0 (21.4 ± 2 mm Hg versus 33.7 ± 5 mm Hg, respectively; p = 0.09) or on day 3 (20.2 ± 2.7 mm Hg versus 24.2 ± 5.1 mm Hg, respectively; p = 0.50). We conclude that there was no advantage of low-potassium dextran over Euro-Collins as a flush solution in this 18-hour canine single lung allograft model in which prostaglandin E1 was administered before pulmonary artery flush.