Between 1992 and 1999 at the Oncology Centre in Cracow 138 NSCLC patients after complete resection of the tumour with mediastinal/hilar node involvement were included in the prospective clinical trial. The analysis of the results did not show any improvement of survival in the postoperatively irradiated group. Three-year survival rates with no symptoms of disease in postoperative radiotherapy patients compared to surgery alone group were 30% and 29% respectively. In this study adjuvant radiotherapy significantly improved local recurrence rate from 28% in surgery only group to 9% in postoperatively treated patients.