To prevent prolonged air leakage after lung surgery, we developed a biodegradable polyglycolic acid (PGA) sheet and compared it with an expanded polytetrafluoethylene (ePTFE). Eighteen adult mongrel dogs were used in this experiment. The airway pressures at which air first leaked at the stapled resection margins were measured immediately after surgery in group I (N=5), 2 days after surgery in group II (N=5), and 7 days after surgery in group IIII (N=5), Based on the presence of SLR, there were 3 subgroups in each group: there was no SLR in subgroup a; ePTFE in subgroup b; PGA sheet in subgroup c. The histologic examination was performed 2 months after surgery (N=3). In group I, there was a significant difference in air leakage pressures (mm Hg) between no reinforcement and SLR. We observed the same results in group II and III with statistical significance. However, there was no significant difference between the reinforcement groups. The histologic findings demonstrated more severe adhesions and biodegradation in the dogs in which the PGA sheet was used. Our PGA sheet was considered a useful reinforcement material, because it had a similar threshold for air leakage with the ePTFE with excellent biodegradation.