Purpose : Percutaneous needle aspiration biopsy under the imaging guidance in the diagnosis of intrathoracicdiseases has become a standard practice. Core tissue obtained by automated gun biopsy(AGB) is believed to be morediagnostic than materials from fine needle aspiration(FNA) by many cytopathologists. The authors evauated the roleof automated gun biopsy in localized pulmonary lesions with respect to the its accuracy and complications.Materials and Methods : We performed 107 percutaneous biopsies in localized pulmonary lesions under fluoroscopicguidance among 107 patients: AGB using 18G or 20G was done in 81 patients, and both AGB and FNA was done in 26patients. Results : Biopsy samples sufficient for histologic diagnosis were obtained in 94(87.9%) of 107 patients,AGB in 73(90.1%) of 81 patients and AGB and FNA in 21(80%) of 26 patients. 11 of 13 negative results were due toinadeguate specimen size for the histologic diagnosis or were composed of necrotic areas, and 2 of 13 negativeresults were obtained through nontarget tissue. 10 patients developed pneumothorax and 4 of them required chesttube insertion. Minimal hemoptysis was found in 3 patients. Conclusion : Percutaneous automated gun biopsy underfluoroscopic guidance was easy and simple method of obtaining specimens of good quality and quantity. It may be anuseful procedure in the diagnosis of localized pulmonary lesions.