The present study reports the case of a 45-year-old pre-menopausal woman treated with 6courses of TAC chemotherapy by the pegfilgrastim for preoperative chemotherapy. The patient visited our hospital in February 2010 with the chief complaint of a mass in the right breast. A 40mm tumor in the outer lower area of the right breast and the axillary lymph nodes was palpable. Pathological findings revealed scirrhous carcinoma with an ER(+), PgR(+), HER2(1+), and Ki-67 80%profile. Pre-operatively, the patient underwent 6courses of triweekly TAC(docetaxel[75mg/m / 2], adriamycin[50mg/m2], cyclo- phosphamide[500mg/m2])chemotherapy. Pegfilgrastim(3.6m g)was subcutaneously injected on the next day of each course. The side effect of 6courses of TAC was stomatitis and low back pain(Grade 2). Relative dose intensity(RDI)was not reduced and there was no occurrence of febrile neutropenia(FN). Partial resection of the tumor was facilitated. Pathologically viable tumor cells still lay scattered in the range of 45 mm, and a ductal carcinoma in situ was seen. However, metastasis to axillary lymph nodes was not observed. Radiation therapy(50 Gy)was performed on the residual breast. There was no recurrence, and now she survival free with tamoxifen(20mg/day)of 8 years four months after operation. TAC with pegfilgrastim therapy could be an effective pre-operative chemotherapy regimen in breast cancer.