ObjectiveTo investigate expressions of ALCAM/CD166, Bcl-2, and Ki-67 in breast infiltrative ductal cancer tissues, so as to assess the role of ALCAM/CD166 protein in the carcinogenesis and progression of breast infiltrative ductal cancer. MethodsThe expressions of ALCAM/CD166, Bcl-2, and Ki-67 proteins were examined by immunohistochemistry(ElivisionTM Plus) in 96 breast infiltrative ductal cancer specimens and 30 adjacent normal tissues of breast cancer specimens(control group). The relation between ALCAM/CD166 protein expression and patient's age, tumor diameter, histopathologic grade, axillary lymph node metastasis, or TNM stage of breast infiltrative ductal cancer was analyzed, and the correlation between ALCAM/CD166 expression and Bcl-2 or Ki-67 was analyzed too. Results①In 96 cases of breast infiltrative ductal cancer, the positive rate of ALCAM/CD166 protein expression was 79.2%(76/96), which was significantly higher than that in the control group〔10.0%(3/30), P < 0.01〕.②In the breast infiltrative ductal cancer tissues, the expression of ALCAM/CD166 was related to axillary lymph node metastasis(P < 0.05), but was not related to patient's age, tumor diameter, histopathologic grade, and TNM stage(P > 0.05).③The ALCAM/CD166 protein expression was positively related to Bcl-2(rs=0.307, P=0.001) and not related to Ki-67(rs=0.064, P=0.475). ConclusionALCAM/CD166 protein expression might be related to the apoptosis and metastasis of breast infiltrative ductal cancer cells and it could serve as an important marker for predicting biological behavior and prognosis of tumor.