PURPOSE: Intraductal papilloma of the breast (IDP) is the most common causes of nipple discharge and it is often a solitary, centrally located tumor that most commonly occurs in the fifth and sixth decades of life. There have been many conflicting reports on the malignant potential of IDP. METHODS: From February 2003 to November 2008, we operated 161 patients who were diagnosed with IDP at Konyang University Hospital. A retrospective review of all the pathologic reports and the corresponding radiological reports was undertaken. RESULTS: The mean age of the patients was 43.23 years (SD, +/-10.1). Eighty-three (51.6%) had nipple discharge, 37 (44.6%) had bloody discharge and 46 (55.4%) had yellowish serous discharge. Twenty-four had a mass and 2 had both bloody discharge and a mass. Radiologic significant findings were shown on 20 mammography exams, 71 ductography exams and 157 breast ultrasound exams. Onehundred forty-four (89.4%) patients with IDP or papillomatosis had surrounding pathologic lesions in the operated specimen according to the final pathology, 107 (66.5%) had fibrocystic change, 26 (16.1%) had fibroadenoma, 30 (18.6%) had atypical ductal hyperplasia (ADH), 11 (6.8%) had carcinoma in situ and 4 (2.5%) had invasive ductal carcinoma. During the follow up, 7 patients (4.3%) developed recurrent IDP, 3 patients developed ADH and 5 patients developed carcinoma in situ (4 patients had ductal carcinoma in situ and 1 patient had lobular carcinoma in situ). CONCLUSION: Intraductal papilloma should be closely followed up due to its malignant potential and the surrounding breast tissue with IDP should be carefully evaluated due to the high rate of developing other precancerous lesions.