A 39-year-old premenopausal nulliparous woman presented with severe pain in her right breast, bleeding and pus-like discharge, and a deep ulcer approximately 18 cm in diameter.Contralateral breast metastasis, bilateral axillary lymph node metastases, and multiple lung and bone metastases were detected on computed tomography.Five years previously she had undergone surgery for ovarian cancer and had prematurely discontinued adjuvant chemotherapy because of side effects. Following the administration of pain control, the patient received trastuzumab(Tr)plus vinorelbine(VNR)for her breast cancer as first-line therapy to avoid hair loss.The ulcer on her right chest wall underwent complete epithelialization and the patient's performance status improved from 3 to 0.The pus-like discharge, pain, bleeding, and odor from the breast resolved completely, and 5 months later, her quality of life had improved.The lung metastases also resolved completely.No adverse affects, including hematotoxicity and hair loss, were seen until treatment failure 12.5 months later. Second-line and third-line treatments were performed, but brain metastases developed, and the patient's overall condition deteriorated because of the development of ileus of unknown etiology.She died 21 months later.The patient received all therapies on an outpatient basis. Combination therapy using Tr and VNR is superior in safety and tolerability, and has been considered an option for first-line treatment of metastatic, locally advanced HER2-positive breast cancer.