Background: Endobronchial ultrasound-transbronchial needle aspiration (EBUS-TBNA) is currently performed first for the mediastinal nodal staging of non-small lung cancer (NSCLC). However, unsuspected lymph node metastases leading to upstaging are found during the final histopathologic evaluation of surgical specimens. Purpose of our study was to evaluate the characteristics of upstaged lymph nodes and the its effects on survival in patients with NSCLC. Methods: We performed a retrospective review from 2009 to 2019 at tertiary-care academic hospital. Patients who diagnosed NSCLC with post-operative pathologic N2 positive lymph node were included. Nodal upstaging was defined as the unexpected pathological finding of metastasis in N2 nodes in patients who were presumed to have clinical N0 or N1 with preoperative staging. Results: Of 177 patients with positive N2 node postoperatively, overall rate of nodal upstaging was 53.1% (94 patients). The baseline characteristics did not differ significantly between upstaged and unchanged patients. Upstaged patients were more likely to receive adjuvant chemotherapy compared to unchanged patients. Culprit nodes leading to upstaging were subcarinal (38.3%), paratracheal (36.2%), and aortic nodes (21.3%). The size of upstaged node was less than 5mm in EBUS. Threeyear mortality was not different between two groups, but lower rate of mortality was observed after excluding inaccessible lymph node. Progression-free survival was significantly higher in the upstaged patients. Conclusion: Nodal upstaging was mainly attributed to the small mediastinal nodes or aortic nodes that are not accessible by EBUS-TBNA and did not influence three-year mortality. After excluding inaccessible lymph node, even higher survival was found in the upstaged patients than the unchanged patients with the same stage.