2099 Background: Although meningioma is the most common tumor in the central nervous system (CNS), the incidence, epidemiology, and clinical outcomes have historically been poorly defined. Our analysis follows the implementation of Public Law 107–260, the Benign Brain Tumor Cancer Registries Act mandating collection of non-malignant meningiomas. Methods: Surveillance Epidemiology End Results Program (SEER) 18 registries research data on cases diagnosed during 2004-2009 with meningioma (ICD-O-3 histology codes 9530-9534 & 9537-9539) in brain or CNS primary site (C70.0-72.9, 75.1-75.3 ) were analyzed. Population-based statistics were generated using SEER*Stat 8.0.1 software. Results: A total of 35,302 cases (34,718 non-malignant; 584 malignant) were available providing a rate of 7.18/100,000, with meningioma, NOS (9530/0) the most common histology. Rates increased with age (0.13/100,000, 0-19 years; 37.78/100,000, 75+ years). The annual percentage change in incidence rates showed a statistically significant increase of 2.57% over 2004-2009. Significant increases were also observed for males, females, whites, blacks, non-Hispanics, and older age groups. The gender ratio M:F was 0.35 in the 0-49 age group and 0.48 in the 50+ age. Primary site location included cerebral meninges (83%) with almost 5% in the spinal meninges. 51% of cases were diagnosed pathologically versus imaging. However, diagnosis among 85% of spinal cases was surgically based. Older age and females were less likely to have a surgical diagnosis. 3.4% received radiation therapy (RT) with 97% receiving RT following surgery. For grade III or malignant cases, 22% received RT, and in grade 1 and 2 nearly 97% of cases did not receive RT, with older age groups less likely to receive RT. Overall survival was high, except for grade 3 or malignant cases where 5 year relative survival was 61.7%. Conclusions: Our analysis following Public Law 107–260 demonstrates an increasing incidence of meningiomas and provides new information, including a decrease in the gender difference with age. Clinical diagnosis is common and higher in women and older adults. Use of RT is low, even in malignant meningiomas, and employed following surgery. These observations were similar for white and black cases.