PURPOSE: To evaluate the usefulness of the coaxial technique in US-guided breast core biopsy. Materials andMethods : Using the coaxial technique, US-guided breast core biopsy was performed in 49 breast lesions (40patients). Under US-guidance the 17-gauge, 13 cm long introducer needle was positioned proximal to the lesion.Once the needle was in place, the central trocar was removed and was replaced with the core biopsy needle. We usedan 18-gauge, 16-cm-long core biopsy needle with a 17 mm specimen notch. Four to eight tissue specimens wereobtained from each lesion, and the quality and quantity of specimens, procedure time, and complications and theirrate were evaluated. RESULTS: For 48 of 49 lesions, specimens were adequate for histopathologic diagnosis, andthe findings were as follows : six cases of invasive ductal carcinoma, one of ductal carcinoma in situ, 29 offibrocystic disease, eight of fibroadenoma, two of chronic inflammation, and two of sclerosing lesion. In 12lesions agreement between the pathologic results of needle core biopsy and surgical results was 100%. Theprocedure time was about 15 minutes and no significant complications were noted. CONCLUSION: In breast corebiopsy, the coaxial technique is simple and time-saving, and compared with stan-dard breast core biopsy, may alsobe less traumatic and decrease the potential risk of seeding the biopsy tract with malignant cells.