Recent studies of malignant testicular tumors report a correlation between vascularization, biologic behavior, radiosensitivity, and chemotherapeutic response of the tumor. Postoperative angiographies of malignant testicular tumor specimens (seminoma n = 4, nonseminoma n = 12) showed the following results: Contrary to the symmetric vascularity pattern of normal testes, seminomas were hypovascular, well-defined from normal testicular tissue and not neovascular. Nonseminomas showed isovascularity (n = 5) or hypovascularity (n = 7) but with focal hypervascular areas in the tumor (n = 10), and pathologic neovascularization. Present angiographic studies reveal marked differences in the vasculature pattern of malignant testicular tumors. In nonseminomas, focal hypervascular or neovascular areas as centers of a high-growth rate correlate well with comparable cell kinetic studies. Assuming a similar growth behavior in metastases, the vascularization type of these growth centers theoretically favors the efficient use of chemotherapeutic agents.