Objective By detecting the expression of caveolin-1 in osteosarcoma tissues,to explore its possible roles in the occurrence,progress and metastasis of osteosarcoma and its relationship with clinicopathological features.Methods The expression level of caveolin-1 protein in 48 osteosarcoma tissues and 24 normal bone tissues were detected by immunohistochemistry of SP method.Its relationship with clinical and pathological features were also analyzed.Results among the 48 osteosarcomas examined,38 were stained weak or negative for caveolin-1,whereas the strong caveolin-1 staining was observed in all the 24 normal bone tissues.The absorbent optical density value of caveolin-1 protein in osteosarcoma tissues and normal bone tissues were(0.2292 ± 0.0329) and(0.6428 ± 0.0028),respectively.The expression of caveolin-1 in osteosarcoma tissues was significantly lower than that in normal bone tissues (t =21.48,P ＜ 0.01 ).Caveolin-1 protein expression was significant correlated with the pulmonary metastasis of tumors ( t =11.84,P ＜ 0.05 ),but had no correlation with nge,sex,tumor size and pathologic grades.Conclusion The low expression of caveolin-1 may participate in osteosarcoma invasion and metastasis,and may be a new prognostic molecular marker for osteosarcoma and a new therapeutic target for tumor.