In recent years, a number of investigators have shown that combining signal transduction agents with ionizing radiation results in significant antitumor effects without an increase in normal tissue toxicity. There are numerous lines of evidence that Histone deacetylase (HDAC) inhibitors have been shown to enhance the radiosensitivity of tumor cells in vitro and in vivo 1-6. Vorinostat (Zolinza, suberoylanilide hydroxamic acid - SAHA) a potent histone deacetylase, has recently been approved for clinical use for cutaneous T-cell lymphoma. It has the potential to inhibit tumor growth and proliferation7-13, tumor angiogenesis14 and enhance radiation response15 with minimal toxicity. This phase I study, is based on the range of efficacy of Vorinostat and its ability to cross the blood-brain barrier. This study will evaluate the safety of combination of Vorinostat and daily-fractionated radiation therapy. This information is critical for any combined future combined modality trials that involves radiation therapy to the brain.