Abstract: Objective: To observe the expression of thrombospondin-1 ( TSP-1) separately in prostatic carcinoma, and its relationship with the angiogenesis. Methods: The expression of TSP-1 and the value of microvessel density (MVD) were studied in 22 prostatic carcinoma patients using immunohistochemistry. Results: Positive expression of TSP-1 protein detected in16 of the 22(72.7%) cases. Most positive staining for TSP-1 was seen in the cytoplasm of the cancer cells, some was in the extracellular matrix. The mean MVD in 22 cases with prostatic carcinoma was 71.21±31.14 vessels per 100 field of vision. Tumors with a high expression of TSP-1 showed a high value of MVD and the correlation between TSP-1 immunocompetence and microvessel density was highly significant (r=0.54, P=0.009). Conclusions: The TSP-1 is strongly expressed in most prostatic carcinoma and were associated with neovascularization. TSP-1 is likely to contribute to the extensive neovascularization and increased TSP-1 expression might participate in angiogenic phenotype in prostatic carcinoma.