Purpose: To exam the relationship between HER2 over-expression and different adjuvant chemotherapies in breast cancer. Patients and Methods: A total of 1625 primary breast cancer patients who received post-surgery adjuvant chemotherapy in Tianjin Cancer Hospital,China,from July 2002 to November 2005 were included in the study. Among them,600 patients were given CMF (CTX+MTX+5-Fu) regimen,600 given CEF (CTX+E-ADM+5-Fu) regimen,and 425 given anthracyclines plus taxanes regimen,with mean follow-up time of 42 months. Results: In CMF treatment group,the 3-year disease free survival (DFS) in HER2 over-expressed patients was lower than that of the HER2-negative ones (89.80% vs 91.24%,P=0.0348); in node-positive subgroup,the 3-year DFS was 84.72% in HER2 over-expressed patients,and 90.18% in the HER-2-negative ones (P=0.0271). Compared to CMF regimen,anthracyclines and anthracyclines plus taxanes regimens are more effective (P<0.05) in node-positive HER2 over-expression than those in the node-negative. Conclusion: HER2 over-expression is an independent index for predicting poor prognosis and short DFS for breast cancer patients. HER2 over-expressed patients are resistant to CMF regimen chemo-therapy,but sensitive to anthracyclines-based or anthracyclines plus taxanes regimen. HER2 expression can be taken as a marker for therapies in breast cancer. Patients: A total of 1625 primary breast cancer patients who received post-surgery adjuvant chemotherapy in Tianjin Cancer Hospital, China, from July 2002 to November 2005 were included in the study. Among them, 600 patients were given CMF (CTX + MTX + 5- Fu) regimen, 600 given CEF (CTX + E- ADM + 5- Fu) regimen, and 425 given anthracyclines plus taxanes regimen, Results: In CMF treatment group, the 3-year disease free survival (DFS) in HER2 over-expressed patients was lower than that of the HER2-negative ones (89.80% vs 91.24% The 3-year DFS was 84.72% in HER2 over-expressed patients and 90.18% in the HER-2-negative ones (P = 0.0348); Compared to CMF regimen, anthracyclines and anthracyclines plus taxanes regimens are more effective (P <0.05) in node-positive HER2 over-expression than those in the node- negative. Conclusion: HER2 over-expression is an independent index for predicting poor prognosis and short DFS for breast cancer patients. HER2 over-expressed patients are resistant to CMF regimen chemo-therapy, but sensitive to anthracyclines-based or anthracyclines plus taxanes regimen. HER2 expression can be taken as a marker for therapies in breast cancer.