The effect of preoperative irradiation and antineoplastic agents on healing at the site of bronchial anastomosis was investigated using rats. The bursting pressure in irradiation group and combined irradiation and chemotherapy group was significantly lower than in control and chemotherapy group at day 5 after operation. There was no significant difference in bursting pressure in all groups at day 7. The histologic finding of the anastomosis with H & E stain showed that submucosal connective tissue had not regenerated, and defects were seen in the submucosal tissue in irradiation and combined therapy group at day 3 and day 5. But, the connective tissue had matured in irradiation group at day 7 compared with control group. In conclusion, this study demonstrated that the healing of bronchial anastomosis was markedly delayed in early postoperative days in the rats receiving irradiation and combined therapy.