Malignant gliomas are the most common primary brain tumors. They are highly aggressive tumors characterized by a recurrence rate of virtually 100%. Despite significant advances in neuroimaging and neurosurgical techniques, the median survival time of patients with glioblastoma multiforme remains 12 to 18 months. Malignant gliomas are characterized by rapidly dividing cells, which invade into the normal brain, and a high degree of vascularity. Recent experimental evidence indicates that tumor-related angiogenesis contributes significantly to the malignant phenotype.