Fifty-five patients were investigated using transbronchial lung biopsy through the flexible fibreoptic bronchoscope under fluoroscopic guidance, 51 by the transnasal route under local anaesthesia, two via an endotracheal tube whilst undergoing assisted ventilation and two by the same route under general anaesthesia. Multiple specimens of lung tissue subjects with diffuse pulmonary disease and in 16 of 32 (50%) with localized lesions, giving a positive yield of 64% of all cases. The only complication was an haemoptysis of 50 ml in one patient. Our results suggest that transbronchial lung biopsy is a relatively safe procedure which gives results comparable with other lung biopsy techniques.