Transbronchial lung biopsy through the fiberoptic bronchoscope was done in 15 patients, and adequate pulmonary tissue was obtained in 14 (93.3%). A pathologic diagnosis was made in nine patients (64.3%), and through direct histologic examination of lung tissue in two patients certain disease entities were excluded, thus significantly influencing treatment. There was no significant hemorrhage and only one small pneumothorax occurred.