Diagnosis of mediastinal/hilar lymph nodes and tumours is often challenging for patients with previously treated thoracic malignancy, especially when they have a history of thoracotomy. Endobronchial ultrasound with transbronchial needle aspiration (EBUS-TBNA) has been proposed as a safe, less-invasive modality for such patients. We retrospectively evaluated the role of EBUS-TBNA in the assessment of newly developed mediastinal/hilar abnormalities in patients with previously treated thoracic malignancy. Of 79 patients who underwent EBUS-TBNA between July 2009 and July 2011, 14 patients (18%) had a history of treatment for thoracic malignancy. In all patients, malignancy was confirmed again for the newly developed mediastinal/hilar abnormalities and three of them (21%) presented with a different pathology from the previous malignancy. Out of 14 patients, 12 had a history of thoracotomy and EBUS-TBNA was a useful, less-invasive diagnostic method particularly for these patients. Out of 14 patients, 11 (79%) had a history of lung cancer and 10 of them (91%) had received surgical resection. In conclusion, we confirmed that EBUS-TBNA obtained the pathological diagnosis in a less-invasive manner in all cases. Despite the small number of cases, our results can reveal the usefulness of EBUS-TBNA particularly in patients with previously treated thoracic malignancy.