Background Neoadjuvant chemotherapy provides an excellent model for evaluation of potential predictive factors.The objective of this study was to evaluate the predictive value of different biological factors in breast cancer patients treated with neoadjuvant taxane and anthracycline chemotherapy.Methods One hundred and thirty-five patients treated with 4 cycles of neoadjuvant taxanes and anthracycline were included in this retrospective study.Using pretreatment biopsy materials,immunohistochemical studies were performed for estrogen receptor(ER),progesterone receptor(PgR),HER-2,Ki-67 and p53 protein expression.The associations among biological markers and clinical and pathological complete response (pCR)were analyzed.Results The overall clinical response was 86%,including 33%clinical complete response(cCR)and 53%clinical partial response.The pCR was iust 17%.In the univariate analysis,only HER-2 overexpression was predictive of cCR to neoadjuvant chemotherapy(P=0.018).No significant associations between other biological factors and cCR were found.Absence of ER,PgR expression and overexpression of HER-2 were predictive of the pCR(P=0.002,0.001,0.01,respectively).Ki-67 and p53 failed to show an association with pCR.In multivariate analysis,overexpression of HER-2remained as an independent variable in predicting the cCR(P=0.021).However,negative ER was the only parameter that maintained statistical significance in predicting the pCR(P=0.001).Conclusions Patients with overexoression of HER-2 and negative hormonal receptor status are much more likely to respond to neoadjuvant taxane and anthracycline chemotherapy than those with the opposite characte ristics.These factors could serve as predictive markers for this regimen.