We experienced a case of locally advanced breast cancer achieving a significant improvement by using a combination of docetaxel(DOC), cyclophosphamide(CPA)and trastuzumab as a primary systemic therapy.The patient was a 54-year-old woman suffering from a right breast mass, who was referred to our hospital and diagnosed with HER2-positive breast cancer with subclavicular lymph nodes metastases.The combination therapy of DOC(75 mg/m / 2), CPA(600 mg/m2)and trastuzumab(loading dose 8 mg/kg, then 6 mg/kg)for 6 courses at q3 week intervals, was started as the primary systemic therapy. After 6 courses of treatment, a right modified radical mastectomy was performed.There were a little breast cancer cells in the breast, and no axillary lymph node metastases.The combination chemotherapeutic regime with DOC, CPA and trastuzumab seems to be useful for treatment of HER2-positive breast cancer.