ABSTRACT Objective To investigate the value of contrast-enhanced ultrasound (CEUS) in evaluating tumor response to neoadjuvant chemotherapy(NAC) in breast cancer. Methods The study included 51 breast cancer patients who received NAC and surgical treatment. All of the patients underwent CEUS examination before and after NAC. Changes of parameters of the CEUS were evaluated before and after NAC. Results The parameters of CEUS can predict final pathologic response. The area of the perfusion defect and penetrating vessels was more often found in non-response group before NAC than response group (P<0.05). Response group showed significantly lower peak intensity, lower regional blood volume and regional blood flow and higher time to peak than non-response group (P<0.05). Conclusion CEUS is effecting in assessing and predicting the response of breast cancer patients undergoing NAC KEY WORDS contrast-enhanced ultrasound; breast cancer; neoadjuvant chemotherapy; quantitative analysis