Over a period of recent 2 years, 30 patients of peripheral lung lesion who were not diagnosed pathologically through bronchial brushing, transbronchial biopsy or sputum microbiologic or cytologic examination, underewent percutaneous fine needle aspiration biopsy under ultrasonic guide, in the department of diagnostic radiology of Chungnam and Gyeongsang National university Hospital. With 3.5 or 5MHz sector probe with or without puncture unit or linear array puncture probe, 20-22G Westcott-Lee or Chiba needle was inserted tangentially into the peripheral lung mass by intercostal, supraclavicular, infraclavicular or subcostal approach. the aspirate was placed on glass slides(fixed or dried in air), collected in test tube(to examine cell block or culture) for microbiologic, cytologic and/or tissue diagnosis. There were 15 benign lesions and 15 malignancies. The diagnostic sensitivity was 94% concerning malignancy versus benignity, and 70%(80% if suspected cases are included) cons dering the specific cell type or etiologic organism as well. Two cases were false negative probably due to inadequate material. There was small asymptomatic pneumothorax in one patient. The diagnostic value compared to percutaneous fine needle aspiration of peripheral lung lesions under fluoroscopic or CT guide was discussed. Ultrasonically guided percutaneous fine needle aspiration biopsy of peripheral lung lesions which can be detectable by ultrasonography is not only a complementary method compared to those under fluoroscopic or CT guidance. but also it probably should be the method of first choice due to its simplicity, safety, feasibility, accuracy, ease, speed and low rate of complications.