PURPOSE: Triple negative breast cancer (TNBC) has had poor prognosis compared with the luminal subtype. And there has been no benefit from doxorubicin. However, the addition of paclitaxel is known to improve both disease-free survival (DFS) and overall survival (OS). The aim of our study was to assess the effect of the addition of paclitaxel after adjuvant chemotherapy with doxorubicin plus cyclophosphamide in TNBC. METHODS: We randomly selected 87 women from 104 women with TNBC who had been randomly assigned to receive doxorubicin (60 mg per square meter of body-surface area) plus cyclophosphamide (600 mg per square meter) for four cycles, followed by four cycles of paclitaxel (175 mg per square meter) or two more cycles of doxorubicin plus cyclophosphamide. Due to predictions of clinical outcomes in women who receive adjuvant paclitaxel based chemotherapy, immunohistochemical analyses of these tissue specimens for CK5/6 were used. RESULTS: Among patients with TNBC, 24 patients (27.6%) were classified as CK5/6-positive triple negative type. Twelve patients were classified as paclitaxel chemotherapy group and 75 patients were classified as no paclitaxel group. No interaction was observed between DFS or OS and paclitaxel regimens. CK5/6 was, however, not associated with a significant benefit from paclitaxel in our study. CONCLUSION: In our study, the addition of paclitaxel after adjuvant treatment with doxorubicin (<60 mg per square meter) is not associated with DFS or OS in TNBC.