Results of transthoracic needle biopsy have been evaluated on the basis of fourteen years experience comprising 5300 procedures on 2726 patients. In 90.7% of the cases a diagnosis was established. Of these, 46.4% showed cytological evidence of primary or secondary malignancy. In 2.4% false positives and in 3% false negatives were noted. The most important complication was found to be pneumothorax, which was noted in 27.2%, but these cases did not as a rule call for treatment. Hemoptysis was observed in 2-5%. There was minor local bleeding around the lesion in 11% of the patients but this only required observation. In one case out of 1264 malignancies an implantation metastasis was found. There was a single case of air embolism with spontaneous recovery, but no mortality in this series. In our experience, needle biopsy represents a minor, inexpensive and safe procedure, which--with a simple technique--permits a direct approach to all kinds of localized lung lesion with a high degree of accuracy.