The left lungs of 14 mongrel dogs were isolated, preserved, and then reperfused for 120 min. Three groups of lungs were investigated: group 1, nonpreserved lungs (control n = 5); group 2, lungs were flushed with UW solution and cold-stored (4-6 degrees C) in the same flush solution for 24 hr (n = 4); and group 3, lungs flushed and cold-stored with modified Euro-Collins' solution for 24 hr (n = 5). Airway pressure (AWP), static lung compliance (Cst), and pulmonary vascular resistance (PVR) 120 min after reperfusion were significantly higher in group 3 compared with the lungs in group 1 and group 2. AWP was 18.7 +/- 3.9 in group 1, 21.1 +/- 3.8 in group 2, and 33.8 +/- 9.2 ml/cmH2O (mean +/- SD) in group 3 (P less than 0.05). Cst was 14.0 +/- 3.5, 10.8 +/- 1.5, and 6.2 +/- 1.2 ml/cmH2O, respectively (P less than 0.01). Pulmonary vascular resistance was 125 +/- 16, 120 +/- 42, and 410 +/- 108 mmHg/L/min (P less than 0.05). We conclude that UW solution is useful for hypothermic canine lung preservation.