The role of surgery in the treatment of patients with stage IIIa non-small cell lung cancer (NSCLC) and mediastinal node involvement is examined in this best evidence topic according to a structured protocol. A total of 579 papers were identified using the outlined search, 12 of which were deemed to represent the best available evidence. From the data summarized, we conclude that surgery, as part of a multimodality therapeutic approach, offers a survival benefit for patients with resectable N2 NSCLC. Overall five-year survival rates following primary resection ranged from 17% to 20% (four studies). Improved five-year survival was demonstrated with multimodality therapy (19-45%; 13 studies). Subgroup analysis demonstrates a five-year survival of 30.5% with postoperative chemo-radiotherapy, 22.2% with chemotherapy alone, and 27% with radiotherapy alone. In our review, we address three major issues regarding the management of stage IIIa NSCLC, the first of which is primary vs. postinduction surgery. The largest cohort series to date is the International Association for the Study of Lung Cancer Staging Committee paper on nodal disease, which reports that patients with single-zone N2 disease had the same survival outcome as patients with multizone N1 disease. The second issue is that of randomized vs. cohort studies: there have been five randomized trials reporting similar outcomes and hence equipoise. The third issue is postinduction staging. All studies evaluated reported a better outcome in patients with ypN0 (i.e. postinduction N0 disease). However, surgery should not be denied to patients with ypN1-N2, as there is evidence to demonstrate a significant improvement in survival time in all patients able to undergo surgery after induction chemo-radiotherapy. In conclusion, although some of the evidence available is equivocal regarding the survival benefit of resection for stage IIIa N2 disease, the authors believe surgery should be considered as part of a multimodality therapeutic strategy for patients with advanced nodal disease.