Abstract: Objective To explore the expression and clinical significance of small breast epithelial mucin（SBEM） and human mammaglobin（hMAM） in breast cancer patients. Methods The expression of SBEM mRNA and hMAM mRNA in peripheral blood samples of 109 primary breast cancer patients and 25 controls（5 healthy donors and 20 other tumor patients）were detected by RTPCR. The percentages of SBEM+/hMAM+ cell were measured by flow cytometry（FCM）. The relationship between them and clinicopathologic features were analyzed. Results RT-PCR results showed that SBEM mRNA and hMAM mRNA only expressed in peripheral blood of breast cancer patients， while no expression was found in that of controls. FCM showed that the percentages of SBEM+ and hMAM+ cells in peripheral blood were 55.9％（61／109） and 40.4％（44／109） in breast cancer， much higher than 10％ in controls. Both SBEM mRNA and hMAM mRNA expression were related to TNM stage and lymph node metastasis， but not to age， tumor size， hormone receptor and C-erbB2. ConclusionSBEM mRNA and hMAM mRNA highly expressed in peripheral blood of breast cancer， and the united detection of them may be helpful to judge hematogenous micrometastasis of breast cancer.