Integration of intraoperative radiotherapy (IORT) with combined treatment of non-small cell carcinoma of the lung seems to be promising. Of particular interest are studies of morphological changes in the bronchial epithelium under the influence of large single dose of radiation (15 Gy). Our clinical investigation included patients with non-small cell carcinoma stage III who had received different schedules of treatment at the Center's clinics. Examination was carried out of biopsy material sampled from the bronchus stump as well as from the contralateral segment of the bronchial tree following combined therapy. Exacerbation of the chronic process in the bronchus stump after IORT was reported. One month after bronchial resection, 80% of patients suffered from catarrhal sclerosing bronchitis. Its progression triggered on bronchial sclerosis in 20%. Catarrhal sclerosing bronchitis in the contralateral segment of the bronchial tree occurred in 60%; there was no significant correlation between catarrhal sclerosis, on the one hand, and the initial condition of the bronchus, on the other. In the control group, there were also signs of chronic bronchitis exacerbation on the site of operation. On the whole, the distribution of patients by bronchitis patterns remained unchanged.