Abstract: Objective 　To investigate the expression of osteopontin mRNA and it s correlation with clinicopathologic features of osteosarcoma and elucidate its role in tumor invasion and distant metastasis. Methods 　The expression of OPN mRNA was detected by semi-quantitive RT-PCR. The relationship between the relative content of OPN mRNA and clinicopathologic features of osteosarcoma was analyzed. Results 　In 58 osteosarcoma tissue samples, the rate of OPN mRNA high-level expression was 81. 0 % (47/ 58) .However, the high-level expression rate in all 25 cases of relative normal osteosarcoma was 16. 0 % (4/25) . The expression of OPN mRNA was associated with the differentiation degree, scope of tumor invasion, years of age and GTM staging, but had no correlation with sex, tumor location and diameter. The 58 patients were followed up for 12～24 months (mean 18 months) . The OPN mRNA high-level expression group (47 cases) had recurrence in 20 patients and death in 7 patient s, whereas the low-level expression group (11 cases) had only 3 cases with recurrence and 1 case dead. Conclusion 　OPN mRNA is overexpressed in osteosarcoma and it reflects the progression of diseases and association with poor prognosis of osteosarcoma. The role of OPN playing in the process of distant metastasis of osteosarcoma is required a further study.