Background: This study evaluated efficacy and safety of bevacizumab (BEV) added to the post-radiation treatment phase for patients with newly diagnosed glioblastoma (GBM). Methods: Sixty-two participants with newly diagnosed GBM were enrolled between May 2007 and June 2010. Participants received standard radiation therapy (RT) within 6 weeks of surgery, and concomitant administration of temozolomide (TMZ). Four weeks after radiation, treatment with TMZ (Days 1-5 of a 28 day cycle) with BEV, (days 1 and 15 of a 28 day cycle) was started, and continued until disease progressed or adverse effects indicated need to stop treatment. Analyses were completed for all participants by intention to treat (ITT), with progression-free survival (PFS) and overall survival (OS) serving as primary and secondary endpoints respectively. Results: Subbjects completed a mean of 7.7 (range 0-29) cycles of post-RT with BEV and TMZ. Twenty participants (32%) were unable to proceed to the post-RT phase. The forty-two participants who did proceed to the post-RT phase completed a mean of 11.5 cycles of treatment. Thirty-eight participants (61%) stopped the study due to disease progression; 6 participants (14%) voluntarily discontinued treatment after 24 cycles with at least stable disease. At a median follow-up time of 24 months, median progression-free survival (PFS) for all participants was 8.8 months while median overall survival (OS) was 16.5 months for all participants. Ly with These results also compare favorably with recently reported results from the AVAglio study (PFS = 10.6 mo.). The toxicity profile was consistent with that reported in similar studies. MGMT promoter methtion.ylation status is under investiga Conclusions: Participants in this study demonstrated a median 1.9 month PFS benefit as compared to the 6.9 median OS reported by Stupp, et al. (2005) and a median 1.9 month OS benefit as compared to the 14.6 month median OS reported by Stupp, et al. (2005). Results suggest that the addition of bevacizumab to the post-RT phase of treatment improves both PFS and OS for persons with GBM despite the high percentage of participants being unable to progress to post-radiation treatment. Clinical trial information: NCT005906.