In patients with suspected sarcoidosis histological confirmation is generally desired. In 40 patients with the ultimate diagnosis of sarcoidosis transbronchial lung biopsy during fiberoptic bronchoscopy revealed in 83% noncaseating granulomas. With 5 biopsies per patient a positive result was obtained in 20 of 25 patients (80%) with radiographic stage I disease, in 6 of 7 (85%) with stage II disease and in 7 of 8 (87%) with stage III disease. The only complications were two small pneumothoraces and two hemorrhages. Transbronchial biopsy with its low morbidity and high diagnostic yield can be recommended as an initial procedure in diagnosing sarcoidosis.