Background: In mediastinal lymph node sampling in non-small cell lung cancer (NSCLC) it is important to determine the appropriate treatment as well as to predict an outcome. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a recently developed, accurate, safe technique in patients with NSCLC for sampling mediastinal lymph nodes. We sought to determine the usefulness of EBUS-TBNA in mediastinal staging with NSCLC considered to be operable. Methods: We retrospectively reviewed the records of 142 patients who underwent EBUS-TBNA for mediastinal staging in the Asan Medical Center, Korea from July 2008 to July 2010. If patients were in an operable state, they underwent subsequent surgical staging. Diagnoses based on biopsy results were compared with those based on surgical results. Results: We performed EBUS-TBNA in 184 mediastinal lymph nodes in 142 NSCLC patients. Almost all of the EBUS-TBNA samples were from the lower paratracheal (112, 60.9%) and subcarinal (57, 31.0%) lymph nodes. In 142 patients, 51 patients (35.9%) were confirmed with malignant invasion of the mediastinal lymph node by EBUS-TBNA and 91 (64.1%) patients were not confirmed. Among the 91 patients, 64 patients (70.3%) underwent surgical staging. 3 patients (4.7%) who were misdiagnosed by the EBUS-TBNA were confirmed by surgery. After Diagnostic sensitivity of EBUS-TBNA, the prediction of mediastinal metastatsis was 94.4% and specificity was 100%. The procedures were performed safely and no serious complications were observed. Conclusion: We demonstrated the high diagnostic value of EBUS-TBNA for mediastinal staging.