Abstract: Purpose:To evaluate the diagnostic value and complications of CT-guided biopsy of thoracic lesions using 20-gauge(20G) cutting needle.Materials and Methods:We retrospectively analyze the diagnostic outcome of 72 cases of CT-guided biopsy of thoracic lesions using 20G coaxial cutting needles:5 cases with mediastinal lesions,5 cases with plural lesions,other 62 cases with pulmonary lesions.Sensitivity,specificity,and diagnostic accuracy were calculated,complications and the relative factors were evaluated.Results:Biopsy diagnosis:58 cases were malignant,8 cases were benign,6 cases were non-specific.All cases were finally proved by surgical operation and clinical follow-up.The diagnostic accuracy was 95.8%(66/72).The diagnostic sensitivity of malignant lesions was 95.1%(58/61),specificity was 100%(11/11),no false-positive result was found.6 cases(8.3%) had complications.Pneumothorax occurred in 4 cases(5.5%),pulmonary alveolar hemorrhage occurred in 1 cases(1.4%),hemoptysis occurred in 1 cases(1.4%).Conclusions:CT-guided biopsy using 20G cutting needles is a useful technique for the diagnosis of thoracic lesion with high accuracy and low complications.