Bevacizumab, a humanized monoclonal antibody designed to inhibit vascular endothelial growth factor, is effective in combination with chemotherapy against malignant gliomas. We examined the therapeutic effects and toxicity of bevacizumab as a single agent for the treatment of recurrent malignant glioma. This is a retrospective analysis of a case series of 18 adult patients, diagnosed with recurrent WHO grade III and IV gliomas. Patients were divided into two groups: group A (n=8) received bevacizumab at a dose of 10 mg/kg every two weeks; group B patients (n=10) were treated with salvage chemotherapy of lomustine (n=4), liposomal doxorubicin (n=4), temozolomide (n=1), or the combination of procarbazine, lomustine, and vincristine (n=1). The main study outcome measure was the 12-month progression-free survival probability; the objective radiological response was a secondary endpoint. Half of the patients treated with bevacizumab remained progression-free at 12 months as compared to none in group B (log-rank p=0.0067). In addition, 7/8 patients in group A showed a radiological response as compared to 4/10 in group B. Toxicity was mild and no intracranial hemorrhage was observed. The finding that bevacizumab has significant activity as a single agent against malignant glioma is important, particularly for those patients who are unable to tolerate traditional chemotherapy.