Background: \- Glioblastoma (GBM) is the most common malignant brain tumor in adults. Patients with GBM are usually treated with surgery, radiation, and chemotherapy. Despite this treatment, most GBMs start growing again. Bevacizumab, a chemotherapy drug, has shown promise in slowing the growth of GBMs. More research is needed to find out whether having surgery before starting bevacizumab is more effective than bevacizumab alone. Objectives: \- To compare surgery plus bevacizumab to bevacizumab alone in adults with glioblastoma. Eligibility: \- Individuals at least 18 years old whose glioblastoma has come back after treatment. Design: * All participants will be screened with a physical exam, medical history, blood tests, and imaging studies. * Participants will be divided into two groups. One group will have surgery followed by bevacizumab. The other group will have the drug without surgery. * The first group will have surgery as soon as possible and will begin bevacizumab 4 weeks after surgery. The second group will start the drug as soon as possible. * Both groups will receive the drug as an infusion every 2 weeks. They will be monitored with frequent blood tests and imaging studies. The infusions will continue for as long as the drug is effective at preventing tumor regrowth. * Participants will be contacted every 4 weeks after they stop taking bevacizumab. They will answer followup questions either in person or by telephone.
* INCLUSION CRITERIA: Previous diagnosis of supratentorial GBM established by WHO histological criteria Age 18 or older NRGS score of 0 to 2 established by the following criteria: * KPS 80 or less (1 point) * Tumor volume 50 cc or greater (1 point) * Tumor involvement of at least 2 of the following brain areas (1 point): * Motor cortex * Language cortex * Areas directly adjacent to the proximal (M1 and/or M2) middle cerebral artery Received initial treatment for GBM with: * External beam radiation therapy * Nitrosourea or temozolomide chemotherapy * Biopsy, subtotal or gross total resection Evidence of recurrence, defined as the appearance or enlargement since previous imaging of a contrast-enhancing mass on T1-weighted MRI Have a non-deep (involving basal ganglia, thalamus, or periventricular region), non-diffuse recurrence judged to be resectable by a neurosurgeon Able to provide informed consent EXCLUSION CRITERIA: NRGS score of 3 Patients requiring biopsy only or other procedures where the goal is not tumor cytoreduction Patients who require urgent or emergency surgery due to symptoms of raised intracranial pressure or herniation Patients who have already received bevacizumab therapy Contraindication to surgery as determined by a neurosurgeon, including bleeding diathesis, unacceptable pulmonary or cardiovascular risk, significant wound healing concerns, or tumor recurrence judged to be inoperable, inaccessible, or diffuse Contraindication to bevacizumab as determined by a neuro-oncologist, including unacceptable end organ function, evidence of acute intracranial hemorrhage, or recent or active use of anticoagulants Contraindication to MRI scanning as determined by a radiologist, including pacemakers or other implanted electrical devices, brain stimulators, some types of dental implants, aneurysm clips (metal clips on the wall of a large artery), metallic prostheses (including metal pins and rods, heart valves, and cochlear implants), permanent eyeliner, implanted delivery pump, or shrapnel fragments Pregnancy