Up to date, it has been reported that the maintenance of ideal function of the preserved lungs were much more difficult than that of the hearts in heart-lung preservation. In this communication the authors have reported the results of experimental study for optimal conditions for preserving better function of the lungs by autoperfusion method by means of heart-lung preparation using 43 dogs. In this study the conditions of the preservation were fixed as following: perfusing blood temperature 29 degrees C, blood flow 30 ml/kg/min., FiO2 30%, FiCO2 5%, tidal volume 15 ml/kg, ventilation rate 10/min., and PEEP 5 cmH2O. Glucose-Insulin-Potassium (0.03 gm., 0.05 U., 0.02 mEq/kg/hr. respectively) were administered continuously by an infusion pump. The results showed that extravascular lung water contents after 6 hours of preservation was 0.79 (mean) +/- 0.01 (SD), which was increased only 1% over than the control group: 0.78 +/- 0.01. There was no significant difference of static lung compliance in two groups: the preserved group was 0.47 +/- 0.02 ml/gm.cmH2O compared to 0.51 +/- 0.06 in the control group. These results suggest that the autoperfusion method on our preserving conditions seems to be very promising and very effective to keep much better condition of the lungs in heart-lung preservation.