A 43-year-old female underwent muscle preserving mastectomy with 6 cycles of adjuvant CMF chemotherapy for breast cancer. She developed multiple lung metastases 16 months later. The metastases were refractory to 3 cycles of CAF administration, and worsened (PD). We therefore added high-dose toremifene to her treatment. This combination therapy brought a marked decrease in the lung metastases. After 9 cycles of CAF with high-dose toremifene therapy, lung metastatic findings had almost disappeared from her chest X-ray. Following this treatment, UFT and toremifene were orally administered for maintenance therapy. Thirty-two months later at present, no increase in these lesions has been observed. High-dose antiestrogen drugs have the potential to inhibit P-glycoprotein. The combination of high-dose toremifene with CAF is potentially effective against ADM-resistant breast cancer.