Over a period of recent 2 years, 30 patients of peripheral lung lesion who were not diagnosed pathologically through bronchial brusing, transbronchial biopsy or sputum microbiologic or cytologic examination, underwent percutaneous fine needle aspiration biopsy under ultrasonic guide, in the department of diagnositc radiology of Chungnam, and Gyengsang National University Hospital. With 3.5 or 5MHz sector probe with or without puncture unitof 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 aspirater was placed onglass slides (fixed or dried in air), collected in test tube (to examinecell block or culture) for microbiologic, cytologic and/or tissue diagnosis. There were 15 benign lesions and 15 malignancies. The diagnostic sensitivitywas 94% concerning malignancy versus benignity, and 70%(80% if suspected cases are included) considering the specific cell type or etiologic organism as well. Two cases were false negative probably due to inadequte material. There was small asymptomatic pneumothorax in one patient. The diagnostic value compared to percutaneousfine 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 byultrasonography is not only a complementary method compared to those under fluoroscopic or CT guidance, but alsoit probably should be the method of first choice due to its simplicity, safety, feasibility, accuracy, ease, speedand low rate of complications.