Background: The purpose of this study is how to use CT-guided needle biopsy for the diagnosis of pulmonary, pleural, and mediastinal mass lesions. Meanwhile, the complications of the procedure were evaluated.Materials and Methods: The pathology results of 150 biopsy specimens, which were obtained from 145 patients aged from 9 to 87 years old (55.3±17.6) referred during a one-year period were reviewed, and the frequency of pneumothorax and hemoptysis were analyzed.Results: Lesion size ranged 1-18 cm [mean (±SD) 6.5±3.4 cm. 95 lesions were contacted to the chest wall. Pathological studies showed that 22 specimens were benign, 61 malignant, 28 nonspecifics, 17 suspicious for malignancy, and 22 insufficient for diagnosis. Risk for pneumothorax and hemoptysis was 6 and 2 percent respectively, which were much better results than previous reports.Conclusion: Although our low complication rate may be attributed to the large size of the lesions and their small distance from the chest wall, we still recommend CT-guided needle biopsy as a useful diagnostic method for thoracic mass lesions.