PURPOSE: It is well recognized that distinguishing benign papillary lesions from malignant papillary lesions on core needle biopsy may pose difficult diagnostic problems. This study was conducted to define the potential role of ultrasoundguided core biopsy for the diagnosis of papillary lesions of the breast. METHODS: Twelve hundred and seventy nine women consecutively underwent 14-gauge core biopsy between January 2004 and December 2006. Of the 1,279 patients, 42 patients (3.2%) had papillary lesions of the breast on core needle biopsy. Of these 42 patients, 35 patients underwent surgical excision or sono-guided vacuum assisted excision. We compared the pathologic results of the excised specimens with the pathologic results on core needle biopsy. RESULTS: Of the 35 patients, 23 patients underwent surgical excision and 12 patients underwent sono-guided vacuum assisted excision. Three patients with intraductal papilloma without atypism on the core needle biopsy were confirmed to have intraductal papilloma accompanied with atypism by the final pathology. All 4 patients with papillomatosis or intraductal papilloma with atypism at core needle biopsy were confirmed to have intraductal papilloma with atypism by the final pathology. There were no patients identified to have breast cancer. CONCLUSION: Our results revealed the accuracy of core needle biopsy for making the diagnosis of papillary lesions of the breast. Surgical excision may not always be necessary for papillary lesion of the breast that is diagnosed on core needle biopsy. Surgical excision is considered in patients with papillomatosis or papillary lesions with atypism seen on core needle biopsy.