Cystic hypersecretory intraductal carcinoma is very rare. The prognosis of this type of breast cancer is very good, similar to other types of intraductal carcinoma. We present what is probably the first case in Taiwan. A 40-year-old woman suffered from a right breast mass for more than one month. An incisional biopsy showed intraductal carcinoma. Amodified radical mastectomy was done. Pathology proved cystic hypersecretory intraductal carcinoma. Her postoperative course was uneventful.