Abstract: Objective: To study the clinical significance of the expression of BSP in primarybreast cancer tissue for predicting postoperative bone metastasis.Methods: Immunohistochemistrymethod (S-P) was used to determined the immunoreacticity to BSP antibody in 70 cases with primarybreast cancer tissues, and expression of ER, PR, C-erb-B2 was also detected.Results: 1) Expressionof BSP in patients who developed bone metastases during the course of disease was significantly highercompared to patients without bone involvement (P<0.01), and the strong positive staining was also high-er (P<0.05). In addition, we aslo found that BSP expression in patients having developed clinically di-agnosed bone metastases was significantly increased than no any metastases and the other metastasesexcept bone (P<0.05; P<0.01), but there was no difference between the latter groups (P>0.05). 2) Ex-pression of BSP was different between patients in the groups of stage Ⅱ and Ⅲ (P<0.05), but no asso-ciation was found between immunoreacticity to BSP antibody and age, estrogen receptor (ER), proges-terone receptor (PR), C-erb-B2 status, primary breast lesions, pathologic histology, axillary lymph nodemetastases (P<0.05). Conclusions: BSP may be a potential indicator at the primary breast cancer tissuelevel for early prediction of breast cancer cells to metastasize to bone after surgery.