PURPOSE: Postoperative radiation therapy (PORT) and postoperative chemotherapy (POCT) can be administered as adjuvant therapies in patients with non-small cell lung cancer (NSCLC). The aim of this study was to present the clinical outcomes in patients treated with PORT-first with or without subsequent POCT in stage IIIA-N2 NSCLC. METHODS AND MATERIALS: From January 2002 to November 2014, the conditions of 105 patients with stage IIIA-N2 NSCLC who received PORT-first with or without subsequent POCT were analyzed. PORT was initiated within 4 to 6 weeks after surgical resection. Platinum-based POCT was administered 3 to 4 weeks after the completion of PORT. We analyzed the outcomes and the clinical factors affecting survival. RESULTS: Of 105 patients, 43 (41.0%) received POCT with a median of 4 cycles (range, 2-6 cycles). The follow-up times ranged from 3 to 123 months (median, 30 months), and the 5-year overall survival (OS) was 40.2%. The 5-year OS of patients treated with PORT and POCT was significantly higher than that of patients with PORT (61.3% vs 29.2%, P<.001). The significant prognostic factors affecting OS were the use of POCT (hazard ratio [HR] = 0.453, P=.036) and type of surgery (pneumonectomy/lobectomy: HR = 2.845, P<.001). CONCLUSIONS: PORT-first strategy after surgery appeared not to compromise the clinical outcomes in the treatment of stage IIIA-N2 NSCLC. The benefit of POCT on OS was preserved even in the PORT-first setting. Further studies are warranted to compare the sequencing of PORT and POCT, guaranteeing the proper use of POCT.