Abstract: Objective To explore the clinical significance of bone sialoprotein and free prostate specific antigen (PSA),total prostate-specific antigen testing and prostate-specific antigen doubling time (PSADT) for prostate cancer bone metastases. Methods A total of 58 cases of patients with prostate cancer from January 2009 to April 2011 in our hospital,were divided into 2 groups:bone metastasis (n=28) and non-bone metastasis (n=30).Sixty benign prostatic hyperplasia patients and 60 normal controls were recruited as hyperplasia group and control group,respectively.The severity of bone pain was evaluated using visual analogue score (VAS).The serum BSP level was detected by ELISA method.The serum f-PSA,t-PSA level were measured by Electrochemiluminescence immunoassay (ECLIA).The PSADT was calculated as PSADT=lg(2)/log(PSA2)-log(PSA1).Determine the diagnostic sensitivity,specificity,and predictive value and cut-off values of these serum tumor markers by ROC curve. Results The BSP levels of both the two patient groups were higher than that of the control group and the hyperplasia group(P<0 05). The BSP level of bone metastasis group was higher than that of the non-bone metastasis group (P<0 05). Pearson's analysis showed that the BSP of bone metastases has a significant positive correlation with VAS pain score (P<0.05). The sensitivity and overall diagnostic efficiency of BSP for determining bone metastasis of prostate cancer is 71.12% and 72.8%.And the sensitivity and overall diagnostic efficiency of PSADT is 84.15% and 82.96%, respectively. When the two tumor markers simultaneity were measured,the specificity,sensitivity and AUC area were 91.26%,89.54% and 0.932，respectively，in the diagnosis of bone metastases of prostate cancer. Conclusion BSP and PSADT are useful markers in diagnosis of bone metastasis of prostate cancer.Combined determination of BSP and PSADT can improve accuracy and positive rate of bone metastasis of prostate cancer significantly.