Abstract: Objective :To observe the change of serum E-selectin concentration in patients of bone metastatic prostate cancer after 89Sr- chloride therapy, and to find out whether radionuclide therapy decreases the expression of endothelial cell selectin-selectin) that participate in the metastatic pro-cess. Methods :Sera were collected from 23 men with multiple skeletal metastases of androgen-inde-pendent prostate adenocarcinoma who received A9Sr- chloride therapy and from 10 age-matched healthy volunteers who serve as normal control. The serum concentration of E-selectin was quantified by en-zyme-linked immunosorbent assay. At the same time, serum prostate specific antigen (PSA) concentradons of all patients were mensurated. Results :Serum E-selectin concentration in patients with the bone metastases of prostatic cancer was significantly decreased after radionuclide therapy. In addition,there was no correlation between the serum E-selectin concentration and the serum PSA levels in pa-bents with skeletal metastases before and after 89Sr-chloride therapy. Conclusions :This result implys that the expression of E- selectin, an important element of metastatic process, may be inhibited by 89Sr-chloride, and the effect may be one of the mechanisms for radionuclide to inhibit the osseous metastases of malignant tumor.