PURPOSE: To assess long term results of excising benign masses using ultrasound (US)-guided, vacuum-assisted core biopsy (Mammotome). MATERIALS AND METHODS: We enrolled 163 patients (197 masses) receiving USguided excision using vacuum-assisted core biopsy and follow-up sonography in this retrospective study. The masses were category 3 as determined by ultrasound imaging according to the Breast Imaging Reporting and Data System (BI-RADS) (n=145) or pathologically confirmed as benign masses by a previous core-needle biopsy although category 4a and 4b (n = 52). Pathology, the presence of hematoma and residual tissue, as well as scar formation were assessed. RESULTS: We diagnosed 190 (96.5%) benign masses, 4 (2.0%) malignant masses, and 3 (1.5%) high-risk lesions. Most (176 masses, 91.2%) were excised completely as demonstrated by the follow-up ultrasound examination. Scar changes were minimal (68.7%) or moderate (31.3%), with regression in 53%. CONCLUSION: US-guided excision using vacuum-assisted core biopsy is effective for the removal of benign breast masses. The majority of scars are minimal, with good cosmetic effect. However, subsequent excision should be done for malignant masses or phyllodes tumor because radiologic absence does not guarantee complete removal.