Abstract: Objective To investigate the expression level and significance of CCL18 in the plasma of breast cancer patients. Methods 20 cases with benign breast diseases and 88 cases with breast cancer were studied.In the 88 breast cancer patients 43 cases received neoadjuvant chemotherapy.The 43 cases of breast cancer patients' blood specimens were collected before and after neoadjuvant chemotherapy,while the others samples were collected before any treatments.36 healthy women were collected as controls.The level of CCL18 in plasms was detected by enzyme linked immunosorbent assay(ELISA). Results The level of CCL18 in the breast cancer patients′ plasma was significantly higher than that in healthy group (P<0.01),and benign disease group (P<0.01).The correlation between the level of CCL18 in the plasma and erestrogen receptor (ER) was negative（P＝0.018）.There was no correlation between the CCL18 level and the neoadjuvant chemotherapy (P=0.431). Conclusion CCL18 is a biomarker of breast cancer,and negative correlation to the expression of estrogen receptor (ER).CCL18 is not an independent predictor for neoadjuvant chemotherapy in breast cancer.