Tumor angiogenesis is believed to be a prognostic indicator associated with tumor growth and metastasis. Microvessel density (MVD) assessment with common endothelial markers such as CD34 has been found to influence prognosis among endometrial carcinoma patients. The CD105/endoglin antibody has been reported to preferentially bind to proliferated endothelial cells in tissues participating in angiogenesis. The aim of this study was to evaluate the quantification of angiogenesis by assessing MVD in endometrial lesions when comparing the performance of anti-CD34 and anti-CD105 in women with benign and malignant endometrial changes. The study included 58 women (37 postmenopausal) with normal, hyperplastic and malignant endometrium in which preoperative transvaginal sonography was performed. Histological results of the removed endometrium were correlated with MVD assessed in "hot areas" where high densities of microvessels were detected within tumoral tissue. Endometrial cancer was confirmed in 37 women (3 premenopausal). Benign hyperplasia (14 cases), secretory or proliferative endometrium (5 cases) or endometrial atrophy (2 cases) was found in the remaining women. Malignant changes were mostly noted as FIGO stage I and II (28 cases) and had a low (1 or 2) histological grade (29 cases). Median MVD's assessed with CD105 and CD34 were 10.4 and 32.3, respectively. Median MVD assessed with CD34 was almost twice higher in women with endometrial cancer than in women with benign endometrium (CD34 MVD = 41.8 vs. 27.6, p=0.004). In cases of CD105 MVD significant differences between women with benign and malignant endometrial changes were also found (CD105 MVD = 11.8, vs. 6.4; p=0.00007). The menopausal status, but not the clinical stage or histological grading was significantly correlated with both CD34 MVD (p=0.02) and CD105 MVD (p=0.0003). A significant correlation was also found between CD34 and CD105 measured MVD (p=0.000001). In conclusion, transition from endometrial hyperplasia to endometrial cancer appears to be accompanied by microvessel density changes. MVD assessed with both CD34 and CD105 antibodies could be used as a potential prognostic factor in women with endometrial cancer. Our study showed that endoglin, by staining the proliferating microvessels could be more specific and sensitive marker for tumor neoangiogenesis than the more commonly used marker, CD34.