PURPOSE: To assess the usefulness of modified coaxial technique for percutaneous multiple core tissue biopsy of small lung and pleural lesion. MATERIALS AND METHODS: The author retrospectively reviewed 37 cases of small (<or=1.5 cm) lung (n=34) and pleural lesion (n=3) in patients who had undergone percutaneous biopsy using modified coaxial technique. All procedures were performed in a CT room, and distance, length and direction were checked on a CT monitor at every five steps of the procedure. During the first step, the site for skin puncture was decided using the slit beam of the gantry and localization grid of the monitor. During the second, puncture direction was decided by referring to the monitor, and a 17G short needle was used as a direction guide and inserted in the chest wall. During the third step, a 22G hub-removable special needle was inserted coaxially through the 17G needle lumen as measured. During the fourth, an 18G guiding cannula was introduced coaxially almost as far as the border of the lesion over the 22G special needle, hub of which had already been removed. During the fifth step, multiple core tissues were obtained in six directions (fanning-out technique) using a 19.5G automated biopsy gun through the guiding cannula. Histopathologic diagnosis and complications were reviewed. RESULTS: Six core tissues of the lesion were obtained in 32 of the 37 cases, four cores in four and three cores in one. Histopathologic diagnosis was made in 35 (95 %) of the 37 cases, and the findings were as follows: adeno-carcinoma(n=15), squamous cell carcinoma(n=1), small cell carcinoma(n=3), metastatic renal cell carcinoma(n=1), tuberculosis(n=7), hamartoma(n=4), cryptococcosis(n=1) and metastatic adenocarcinoma of the pleura(n=3). Hemoptysis was noted in two cases but subsided spontaneously. Pneumothorax occurred in two cases (5 %), and in one of these an 8.3 F catheter was inserted. CONCLUSION: Modified coaxial technique under CT guidance for obtaining multiple core tissues of small lung and pleural lesion, with a single puncture of the pleura in one session of percutaneous biopsy, is useful for histopathologic diagnosis and the treatment of complications.