Background This study was designed in an attempt to determine the influence of neoadjuvant chemotherapy on estrogen receptor (ER),progesterone receptor (PR),human epidermal growth factor receptor 2 (Her-2),and Ki-67 expressions in patients with breast cancer.Methods Pre-and post-neoadjuvant chemotherapy,paired-tumor specimens from 103 patients with breast cancer administrated with anthracycline or anthracycline combined taxane regimen were collected.Immunohistochemical staining for ER,PR,Her-2,and Ki-67 was performed by the DAKO EnVision method.Results Among the 103 cases,five patients (4.9％) had a complete response (CR),82 (79.6％) partial response (PR),15 (14.6％) stable disease (SD),and one (0.9％) progressive disease (PD),yielding an overall response rate (CR + PR)of 84.5％.Nine patients achieved pathological CR.There was a significant decrease in the average index of Ki-67 postneoadjuvant chemotherapy,compared with that before chemotherapy (24.1％ vs.39.7％,P ＜0.001).After neoadjuvant chemotherapy,the changes of Ki-67 in different subtypes of breast cancer were different (P ＜0.001),and these changes correlated with response to neoadjuvant chemotherapy (P ＜0.001).No significant changes in immunohistochemical expression were observed for ER,PR and Her-2.Conclusions Neoadjuvant chemotherapy apparently reduced Ki-67 index in primary breast carcinomas,but profiles for ER,PR and Her-2 were not significantly different before and after neoadjuvant chemotherapy.The change of Ki67 correlated with molecular subtypes and response to neoadjuvant chemotherapy,suggesting that Ki-67 index was a surrogate marker to predict the treatment response of neoadjuvant chemotherapy.