In this multicenter phase II study, patients with newly diagnosed glioblastoma will receive standard treatment, including initial debulking surgical resection (if feasible) followed by high-dose radiation therapy with concurrent temozolomide. After completion of radiation therapy, patients will continue treatment with temozolomide (150mg/m2 days 1-5) and sorafenib (400mg PO bid daily), repeated at 28-day intervals for 6 cycles.