Abstract: Objective:To evaluate the diagnostic significance of percutaneous pulmonary biopsy under CT guidance and to discuss the causes of complication.Methods:CT-guided percutaneous transthoracic incision biopsy was performed in 60 patients with pulmonary masses.The diagnostic accuracy,major complications and the influence factors were reviewed.Results:Aueffective specimens were obtained from the 60 cases(achievement ratio 100%).Final diagnosis was made in 58 cases(diagnostic accuracy 96.6%),including 49 cases of primary pulmonary carcinoma,3 cases of tuberculosis,2 cases of inflammatory pseudotumors,2 cases of metastasis,1 case of sarcoid and 1 case of aspergillosis.The major complications included pneumothorax(13.3%) and pulmonary hemorrhage(16.7%).Pneumothorax and pulmonary hemorrhage were obviously associated with the length of the needle cutting through the air lung(P<0.01).Pneumothorax was not associated with pneumonectasia or location of the lesions(P>0.05).Conclusions:CT-guided pereutaneous transthoracic needle biopsy is a feasible and safe method in diagnosis of pulmonary lesions with high accuracy.Accurate location of the lesions and skillful manipulation are essential in decreasing complications.