Objective:To evaluate the diagnostic accuracy,complications, and usefulness of CT-guided transthoracic needle biopsy of small pulmonary nodules. Methods: Between August 1991 and May 1997,158 patients underwent transthoracic needle biopsy of pulmonary lesions.Thirty-five lesions were presented small nodules,defined as lesions of 2.0 cm or less maximum diameter.A total of 38 biopsies were performed in the 35 lesions. Results: There were 11 benign lesions and 24 cancers (19 primary， 5 metastatic).Transthoracic needle biopsy findings were positive for cancers in 21 cases.In all 3 false negative lesions, only one biopsy was performed.There were 11 true-negative results and no false-positive results. Positive and negative predictive value were 100％ and 79％，respectively. Pneumothorax occurred in 5(13％)of 38 biopsies,but no chest tube placement was necessary. Conclusion:CT-guided transpulmonary biopsy of small pulmonary nodules can produce diagnostic yields comparable with that of larger lesions, and has a definitive diagnostic value of clinical utility.