Background:Meningioma constitutes 20% of the intracranial neoplasms. Followed by surgery as the primary treatment for most patients, radiotherapy becomes indicated in high-grade tumors with incomplete surgical removal. We evaluated the prognostic factors and overall outcome in meningioma patients who underwent radiotherapy.Materials and Methods:In this retrospective analysis, data from all patients with documented diagnosis of meningioma who referred to the Omid and Ghaem Oncology Centers (Mashhad, Iran) from 2002 to 2013 were included. We calculated the overall survival rates using the Kaplan–Meier method and compared the survival curves between groups by the log-rank test.Results:Eighty-three patients with a median age of 50 years (ranging: 16–84) were included. Grade I, II, and III meningiomas were seen in 40 (48%), 31 (37%), and 12 (15%) patients, respectively. Radiation therapy was indicated due to tumor recurrence, incomplete excision, or tumor grade in 32, 8, and 43 patients, respectively. Tumor grade had a significant effect on the overall survival with a 3-year overall survival of 76.7%, 43.5%, and 13.3% in Grade I, II, and III, respectively (P < 0.001). Gender, age, and tumor location were not correlated with the overall survival. Moreover, patients with Grade II and III who underwent total resection had a significantly higher overall survival than those with subtotal resection or biopsy alone (5-year survival rates of 82% vs. 17.1%, respectively; P = 0.008).Conclusion:Tumor grade was the most important prognostic factor in meningioma patients undergoing radiation therapy. In patients with Grade II and III tumors, the extent of surgical resection is significantly correlated with the overall survival.