Objectives:To investigate the clinical significance of the expression level of cytokeratin5/6/18 positive cells in peripheral blood cells from patients with breast carcinoma.Methods:The expression rates of ck5/6/18 positive cells in peripheral blood cells from 56 patients with breast carcinoma were measured and analyzed by flow cytometry.Results:The expression rates of ck5/6/18 positive cells in peripheral blood cells from 56 patients with breast carcinoma was 46.4% and there was significant differences compared with healthy volunteers and the patients with breast benign diseases.The positive rates increased significantly with the pathological staging and show no significant relationship with the ER and PR.Conclusion:The expression of ck5/6/18 positive cells in peripheral blood cells correlates significantly with the pathological staging of breast carcinoma and it could be an effective signal to clinical monitor and prognosis.