An elderly patient with breast cancer received toremifene monotherapy for one year, and about 60% tumor remission rate was obtained. Since viability of the residual tumor was suspected on ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI), lumpectomy was performed under local anesthesia. The histopathological diagnosis was ductal carcinoma in situ (DCIS). The patient did not undergo axillary lymph node dissection or systemic chemotherapy. The patient is alive without disease under postoperative radiotherapy and toremifene treatment. Toremifene monotherapy and/or preoperative adjuvant therapy with toremifene alone may be useful methods for elderly patients with breast cancer considering the patients' quality of life.