Malignant gliomas are the most common and aggressive primary brain tumors in adults. Despite optimal treatment with surgery, radiotherapy, and temozolomide, tumor recurrences are frequent and patients with malignant gliomas continue to have poor prognoses. Malignant gliomas are often highly vascularized, and significant advances have been made in the last few decades in our understanding of the mechanisms of tumor angiogenesis. Recently, bevacizumab, an antibody against vascular endothelial growth factor, has demonstrated significant activity in recurrent glioblastomas, resulting in US Food and Drug Administration approval and raising the prospect for other antiangiogenic drugs now entering clinical trials.