Transbronchial lung biopsy (TBB) was performed during fiberoptic bronchoscopy under fluoroscopic guidance in 133 patients with diffuse or peripherally localized lung diseases without endobronchial lesions. Histological diagnosis consistent with the clinical course and roentgenographic appearance was obtained in 96 patients (72%). In four cases specimens were inadequate for histological evaluation (3%). In 33 cases a diagnosis was not possible even though the specimens were adequate for histological examination. The low complication rate in this series seems due to the selection of patients and the technique used.