Postoperative radiotherapy (PORT), especially using modern technology, for patients with stage IIIA-N2 non-small cell lung cancer (NSCLC) is controversial. We retrospectively investigated 112 patients with stage IIIA-N2 NSCLC who underwent complete resection of the lung tumor in our institution from 1986 through 2003. Among the 91 patients determined suitable candidates for PORT postoperatively, 45 patients received PORT (PORT group) and 46 did not (non-PORT group). We analyzed the correlation between PORT use and clinicopathological characteristics, number of involved mediastinal lymph node stations, recurrence, and survival. Five-year and 10-year survival rates of PORT group were 53.2% and 40.0%, which were superior, however, not statistically different, to those (39.3% and 27.5%) of non-PORT group (P=0.6284). According to the number of mediastinal lymph node stations, PORT was more effective for multiple station metastasis than single station metastasis. The disease-free survival of PORT group was significantly better than that of non-PORT group among the patients with multiple station metastasis. Five-year disease-free survival rate of PORT group and non-PORT group were 41% and 5.9%, respectively (P=0.0220). PORT using modern techniques can reduce local recurrence and improve overall survival especially for patients with multiple station N2. Prospective randomized control trials are warranted.