The objective of the present study was to investigate the role of postoperative radiotherapy (PORT) after radical resection of stage IIIA-N2 non-small cell lung cancer (NSCLC). Subgroups of patients who benefited from PORT were evaluated. A retrospective review of 288 consecutive patients with resected pIIIA-N2 NSCLC at Beijing Chest Hospital (Beijing, China) was performed. Of these patients, 61 received PORT. The 288 patients were divided into PORT and non-PORT groups according to the treatment received. The baseline characteristics of the two patient groups were balanced using propensity score-matching (PSM; 1:1 matching). In total, 60 patients in the PORT group and 60 patients in the non-PORT group were matched. After PSM, the median survival time of the matched patients was 53 months. The 1-, 3- and 5-year overall survival (OS) rates of the PORT patient group were 95.0, 63.2 and 48.2%, respectively, while those of the non-PORT group were 86.7, 58.3 and 34.5%, respectively, and there was no significant difference between the two groups (P=0.056). The 5-year local recurrence-free survival (LRFS) rate in the PORT group was significantly improved (P=0.001). The effects of PORT on OS and LRFS rates were analysed in patients with different clinicopathological features. For subgroups with multiple N2 stations, N2 positive lymph nodes ≥4 and squamous cell carcinoma, PORT significantly increased the OS and LRFS rates (P<0.05). In conclusion, there was no statistically significant improvement in the 5-year OS rate with PORT overall, but there may be subgroups, such as patients with multiple N2 stations, N2 positive nodes ≥4 and squamous cell carcinoma histology, that could be explored as potentially benefitting from improved 5-year OS and LRFS rates with PORT.