Angiogenesis represents one of the most important factors of the tumor proliferation. Renal carcinoma with clear cells is highly vascularized. Knowing numerous quantification systems of tumor angiogenesis, we used a simple one, the evaluation of the relative vascular density. We studied 61 cases with partial or total nephrectomy performed in the Urology Department of Timisoara County Hospital. We correlated the intensity of angiogenesis with a tumor proliferation factor PCNA (proliferating cell nuclear antigen) and with the monoclonal antibody PC10. Correlation of the two immunohistochemical methods with the degree of the tumor differentiation suggested an inverse ratio between vascular density and tumor proliferation degree.