Angiogenesis seems to contribute to tumor growth and the development of metastases. There may be an association between the vascular density of individual tumors and their prognosis. In the present survey we studied 53 cases of renal cell carcinoma investigating possible relationship between histologic grade and microvessel density (MVD) measured by an image analysis system. According to our results MVD was significantly associated with the histologic grade, higher grades being accompanied with a higher MVD. Further studies are needed to investigate a possible connection of MVD with the prognostic role of grade in RCCs.