Objective   To investigate the significance of endoglin in the angiogenesis of ovarian carcinoma.    Methods   Immunohistochemical assay was used to investigate 70 tissue samples of pathologically identified epithelial ovarian tumor (including 31 specimen of benign and 39 of malignant) from December 2000 to December 2003 in our department using monoclonal antibodies against CD34 and endoglin. Microvessels density (MVD) was counted by experienced pathologists.    Results   No significant difference of MVD for CD34 was observed in the ovarian cystadenoma and ovarian carcinoma. In contrast

an increment of MVD for endoglin from low-grade to high-grade dysplasia and that from earlier stage to later stage was statistically significant.    Conclusion   Endoglin may be a valuable marker for assessing neovascularization in the process of ovarian carcinoma development and for predicting the risk of ovarian carcinoma development.