Abstract: Objective：To study the clinical value of determination of serum procollagen Ⅰ carboxy-terminal propeptide (PⅠCP) and carboxyterminal telopeptide of type Ⅰ collagen(ⅠCTP） contents in cancer patients with bone metastases. Methods ：Serum PⅠCP and ⅠCTP contents were measured with ELISA in 41 patients with bone metastases and 39 controls without bone metastases. The patients with bone metastases consisted of ：(1) group A, less than 6 metastases foci, n=20 (2) group B, 6~20 foci, n=12 (3) group C, over 20 foci， n=9. The comparison of bone turnovers among patients with different bone loads was analyzed. Results ：(1) Serum PⅠCP,ⅠCTP contents was significantly greater in patients with bone metastases than without bone metastases（P<0.01） (2) With the increase of the extent of bone metastases, serum PⅠCP elevated， there were significant difference among each grade（P<0.01）. ⅠCTP elevated, there were significant difference between Group C and Group A,B（P<0.01）. (3) Levels of PⅠCP (P<0.01) and ⅠCTP(P<0.05) were correlated with the number of foci. Conclusion ： (1) The determinations of serum PⅠCP and ⅠCTP could reflect the clinical status of metastases size (PⅠCP more sensitive). (2) Levels of PⅠCP correlated well to the number of foci.