Purpose: To retrospectively evaluate the role of postoperative chemoradiotherapy (POCRT) in patients with completely resected non small-cell lung cancer (NSCLC) with N2 lymph node involvement. Methods and Materials: This study included 183 patients from four centers in southwest China who underwent radical section of Stage III-N2 NSCLC without any preoperative therapy. One hundred and four were treated with POCRT and 79 with postoperative chemotherapy (POCT) alone. The median radiation dose to clinical target volume (CTV) was 50 Gy (varying between 48 and 54 Gy), whereas the cycles of platinum-based chemotherapy ranged from two to six with a median of four. Results: The median duration of follow-up was 72 months. The 5-year overall survival rate (OS) was 30.5% in the POCRT group, and 14.4% in the POCT group (p = 0.007). The 5-year disease-free survival rate (DFS) was 22.2% in POCRT group and 9.3% in POCT group (p = 0.003). In a multivariate analysis, N1 nodal involvement (N1+/N2+) was associated with significantly worse OS (HR = 1.454, 95% CI, 1.012-2.087, p = 0.043) and DFS (HR = 1.685,95% CI, 1.196-2.372, p = 0.003). Absence of radiotherapy and treatment with fewer than three cycles of chemotherapy both were poor prognostic factors for both OS and DFS. Conclusions: As compared with chemotherapy alone, adjuvant treatment with both radiotherapy and chemotherapy improves survival in patients with completely resected Stage III-N2 nodal disease in NSCLC. Future study of treatment modality with radiotherapy and chemotherapy is warranted, especially focusing on both Ni and N2 nodal status. (C) 2010 Elsevier Inc.