From May 2009 to December 2010, forty patients underwent endobronchial ultrasound transbronchial needle aspirations (EBUS-TBNA) in our hospital. We examined their medical records to obtain information concerning the diagnosis yields, the sites and sizes of lymph nodes, the number of needle passes, and other complications. The definitive diagnoses were made using EBUS-TBNA in 26 patients (9 lung adenocarcinomas, 4 lung squamous cell carcinomas, 4 small-cell carcinomas, 3 nonsmall cell lung carcinomas, 1 mesothelioma, 1 lymphoma, 3 sarcoidoses, and 1 tuberculosis lymphadenopathy; sensitivity, 74.2%; specificity, 100%). Active epidermal growth factor receptor gene mutation was found in 2 adenocarcinomas using EBUS-TBNA specimens. The median of the longest diameter in 44 lymph nodes from 40 patients was 22 mm (range 10-60), and the median number of needle passes was 2 times (range 1-5). Five patients experienced fever and bloody sputum; however, no severe complications appeared. EBUS-TBNA seemed useful for diagnosing not only mediastinal and hilar lymph-node metastases in patients with lung cancer, but also mesotheliomas, lymphomas, sarcoidoses, and mycobacterium infections.