Background: Transbronchial needle aspiration (TBNA) of intrathoracic lymph nodes has been shown to be useful in the diagnosis and staging of bronchogenic carcinoma. The usefulness of TBNA has not been widely investigated in benign disease other than sarcoidosis. Objectives: We investigated the diagnostic value of TBNA in consecutive patients who were referred to Yedikule Hospital of Chest Disease and Thoracic Surgery because of mediastinal and/or hilar adenopathy. Methods: A total of 29 TBNA procedures were performed in 28 patients who had mediastinal or hilar adenopathy identified by computed tomography of the chest. TBNA of enlarged lymph nodes was performed using a flexible bronchoscope (BF 30T, Olympus) and a 19-gauge needle capable of obtaining core biopsy specimens (MW-319 Mill-Rose Laboratories, Mentor, Ohio, USA) from endobronchial or endotracheal locations. All patients had at least three examinations of sputum smears for acid-fast bacilli prior to bronchoscopy and the results of sputum smears were found to be negative. Results: Adequate lymph node samplings were obtained by TBNA in 23 of 29 (79%) procedures. Diagnostic samples were obtained by TBNA in 20 of 29 (69%) procedures. We were able to make a diagnosis in 20 of 23 (87%) patients in whom adequate lymph node samples were obtained by TBNA. TBNA was the only means of diagnosis in 13 of 28 (46%) patients. The diagnoses provided using TBNA were tuberculosis in all of 10 patients (100%), sarcoidosis in 7 of 8 patients (87.5%), lymphoma in 1 of 2 patients (50%), small cell carcinoma in 1 patient and nonspecific lymphadenitis in 1 patient. No complication was observed and there was only minimal bleeding. Conclusions: We conclude that TBNA, using 19-gauge histologic needles through a flexible bronchoscope, is a valuable tool in the diagnosis of intrathroracic adenopathy, particularly in patients with tuberculosis and sarcoidosis. TBNA should be considered in the diagnosis of intrathoracic adenopathy before other invasive procedures.