Abstract: To evaluate the activity ofhe sequence exposure of Epirubicin(Epi), Taxotere(Tax), and 5Fluorouracil(5Fu) for human breast cancer so as to select the most effective treatment schedule. Methods：The cytotoxic activity of drug on MCF7 was evaluated by sulphorhodamine B assay and the interaction of the different drugs was assessed by median effect principle. The cell cycle and apoptosis were evaluated by flow cytometry. The expressions of p53, bcl2, p21,bax and thymidylate synthase(Ts) were detected by Western blotting. Results：As a single agent, 5Fu exerted a low cytotoxic activity in MCF7 cells. The Epi→Tax sequence induced a synergistic cytocidal effect and enhanced the efficacy of 5Fu. The Epi→Tax sequence blocked MCF7 cells in G2M phase, and the addition of 5Fu forced the cells to progress through cell cycle or killed them. The Epi→Tax sequence induced a significant reduction in basal Ts expression. The sequence of Epi→Tax→5Fu produced a synergistic and highly scheduledependent interaction(CI<1),

Key words: Breast tumour, Epirubicin, Taxus, Sequential chemotherapy, Cell apoptosis