The supervision of the efficacy of therapy with curative aim in inoperable NSCLC focus on clinical and radiological parameters and the survival rate. But the decision about the local tumour elimination lies in the microscopic area, which cannot be controlled neither by laboratory tests nor by radiological examinations. About twenty years ago with support of our pneumologist we carried out bronchoscopies and biopsies depending on the applied radiation dose. It was our intention to take the remission noted by endoscopy as measure for the reaction of the whole irradiated target volume. The bronchoscopies and biopsies were provided at dose levels of 60 and 80 Gy. 90.9% (340/374) of repeated bronchoscopies were realized after a dose of 60 to 80 Gy. The analysis covers 253 bronchoscopies before and 374 between or after radiotherapy with 623 histological or cytological examinations on a total of 253 patients. At the begin of the radiotherapy 50.2% (127/253) had tumour between trachea and a lobar bronchus, after 60 Gy only 13% and after 80 Gy still 1.2% (1/81) had tumour in this area. The macroscopical tumour elimination rose from 41.4% (80/193) after 60 Gy to 79.3% (65/82) after 80 Gy. In contrast and unexpectedly the microscopic negativity decreased from 73.4% (141/192) to 71.6% (58/82). Partially this result is a consequence of the fact that "necrosis" may be either a part of an untreated malignoma or an effect of an irradiation. The combination of macro- and microscopic tumour elimination rose from 20.5% (7/34) after a dose of 60 Gy to 64% (16/25) after total doses of 80 Gy. Only combined negativity had a consequence for local relapse free survival (p = 0.034) and overall survival (p = 0.0002) in comparison with the patients with persistent macro- and/or microscopically detected endoluminal tumour at the final bronchoscopy. The assessment of endoluminal tumour regression as part of the whole irradiated malignoma permits conclusions about the total dose needed. This is a new approach providing at least more local security without augmentation of side effects in comparison with the conventional guidelines.