We substituted autologous lung for the artificial oxygenator to assess reduction of lung injury after conventional cardiopulmonary bypass (CPB). Twelve piglets were randomly divided into two groups. Experimental animals (n = 6) underwent bilateral CPB with autologous lungs perfusion, whereas control animals (n = 6) underwent conventional CPB with artificial oxygenator. Bypass and aortic cross clamping time were 135 and 60 minutes, respectively, for each animal. Lung static compliance (Cstat), alveolus-artery oxygen difference (PA-aO2), tumor necrosis factor (TNF)-alpha, interleukin-6, and wet to dry lung weight ratio (W/D) were measured. A single senior pathologist evaluated the lung specimens after experiments. Cstat of experimental group and control group decreased from 14.31 +/- 1.58 to 12.88 +/- 1.92 ml/cmH2O and from 14.80 +/- 2.32 to 10.48 +/- 1.66 ml/cmH2O, respectively; PA-aO2 increased from 15.71 +/- 1.35 to 62.30 +/- 24.29 mm Hg and from 15.23 +/- 2.87 to 77.85 +/- 11.45 mm Hg, respectively; serum concentration of TNF-alpha increased from 0.40 +/- 0.07 ng/ml to 0.56 +/- 0.15 and from 0.41 +/- 0.06 to 0.75 +/- 0.14 ng/ml, respectively; and the w/d were 6.18 +/- 0.55 vs 6.84 +/- 0.30. Pathological examination also confirmed that structural changes of lung specimens were less in experimental group than in control group. Autologous lung may tolerate nonpulsatile perfusion and be used clinically as a substitute for the artificial oxygenator to reduce lung injury after CPB.