Abstract: ObjectiveTo study the HER-2 expression after the breast cancer neoadjuvant chemotherapy. Methods HER-2 was detected by fluorescence in situ hybridization（FISH） methods after core needle or Mammotome biopsy in 137 cases.Two~Six cycles neoadjuvant chemotherapy (including FEC,TE and AC regimens) later, HER-2 was detected again. Results HER-2 of 22 cases was positive,and 115 cases were negative. 8 cases(including 3 HER-2 positive and 5 HER-2 negative cases) were complete response(CR),91 cases were partial response(PR),24 cases were stable disease(SD),and 14 cases were progression disease(PD).There were 22 cases HER-2 positive(except 8 CR cases) at post-chemotherapy.HER-2 positive cases were still positive after neoadjuvant chemotherapy,while 3 HER-2 negative cases turned to be positive but the change was no significant difference(P>0.05). Conclusion Neoadjuvant chemotherapy might induce HER-2 but down-regulate HER-2 expression.