Over a 24 month period, 35 patients seen consecutively with a pleural or chest wall mass had a percutaneous biopsy using an 18 gauge cutting needle operated by a specially designed, hand held, spring loaded trigger system (Biopty TM, Biopsy instrument, Radiplast A.B. Sweden). Biopsies were performed under local anaesthesia with ultrasound, fluoroscopic, or computed tomography guidance, depending on the site and nature of the lesion. An excellent specimen, consisting of a core of tissue, was consistently obtained and a specific histological diagnosis was possible in 30 patients (28 malignant lesions and two benign lesions). In two patients there was an unequivocal diagnosis of malignancy but the tumour was too necrotic to allow a cell type to be established. In three patients the specimen consisted predominantly of dense fibrous tissue. One of these was a presumed false negative result for malignancy; the other two are presumed true negative results. There were no complications of the procedure.