OBJECTIVE Post-operative radiotherapy (PORT) in non-small cell lung cancer (NSCLC), especially after complete resection, has long been an unresolved dilemma and debated among therapeutic disciplines. We aimed to evaluate the effects of different radiotherapy volumes and techniques on local-regional recurrence patterns and PORT results in patients with NSCLC. METHODS The results of 389 patients who underwent surgery and received PORT at 11 centers were analyzed retrospectively. The surgical margin was positive or closes in 100 (26%) patients. The PORT dose was a median of 50 Gy (36-60 Gy). Intensity-modulated RT methods were used in 68 (17.5%) patients. RESULTS The first recurrence of the patients who developed relapse, local recurrence was found in 77 (19.8%) patients, distant recurrence was found in 95 (24%) patients, and both recurrences was found in 30 (8%) patients. The median time to locoregional relapse was 14 months (1.84-59.7 months). Local-regional recurrence was not significantly higher in patients with positive surgical margins than in negative pa-tients (39% vs. 29%, p=0.1), but the dose administered to these patients was also higher. Mediastinal recurrence occurred in 28 (19%) patients who did not receive radiotherapy to the mediastinum; 25 of these recurrences (89%) were just near or outside the field. Cardiac events became 7% in all groups and did not change according to chosen mediastinal radiotherapy volume. CONCLUSION A clear description of the PORT volumes according to the localization of the primary tumor and the involved lymph nodes would be beneficial in terms of establishing the recurrence/toxicity balance better.