The histopathologic diagnosis of sarcoidosis requires the presence of noncaseatinggranulomas. Transbronchial lung biopsy (TBB) through the fbreoptic bronchoscope has been considered the procedure of choice for patients suspected of having pulmonary sarcoidosis. The purpose of this prospective study was to evaluate transbronchial needle aspiration (TBNA) of mediastinal lymph nodes in the diagnosis of sarcoidosis and to compare this technique with TBB. Thirty-two consecutive patients were grouped according to their chest radiographs into group I (17 patients with hilar or/and mediastinal adenopathy) and II (15 patients with hilar or/and mediastinal adenopathy and pulmonary infiltrates). Sarcoidosis was the final diagnosis in 26 patients and lymphoma in the remaining 6 cases. Non caseating granulomas were found in 24 of 26 patients (92%) by TBNA and in 14 of26 (54%) by TBB. The combined use of both procedures increased the diagnostic yield to 96%%. A mediastinoscopic lymph node biopsy showed "sarcoid "granuloma in the remaining patient with negative TBNA and TBB. The TBNA was the only mode of diagnosis in 11 of 26 patients. There were no significant complications following the procedure. Pneumon 2006,19(2):112-117.