The histological results of transbronchial lung biopsies have been analysed in 109 patients with diffuse or localised lung diseases. This diagnostic procedure is relatively safe, well tolerable and can be carried out in outpatients. In diffuse lung diseases its use can replace the open lung biopsy. The efficacy of this method depends on the availability of biplanar fluoroscopy, the quality of the excisors, the quantity and size of the biopsy material and the technique of the histological handling.