OBJECTIVES:  To estimate the prevalence of Medicare FFS patients 65+ years receiving treatment in 2013 for OAB and to determine what patient characteristics were associated with higher prevalence. METHODS: The 2013 Medicare Beneficiary Part B Carrier Claims File (Carrier), the Part D Drug Event File (PDE), and the Medicare Beneficiary Annual Summary File (BASF) for patients over 65 years were used to calculate prevalence of OAB and the number of patients with OAB among the Medicare FFS population. OAB was defined as having an OAB related diagnosis and/or a Part D claim for an antimuscarinic or mirabegron and/or a CPT code (52287) for onabotulinumtoxinA injection of the bladder. The BASF was linked to the Carrier and PDE Files to determine patient age, gender, and race/ethnicity.  RESULTS: The national prevalence rate of OAB among Medicare FFS patients was 7.17% (N= 2,278,865); the rate was 7.72% among males and 6.74% among females. By race/ethnicity subgroups, the prevalence rate was lower in Blacks (5.8%) and Hispanics (5.86%) compared with Whites (7.43%). Patients 75+ years have a significantly higher OAB prevalence rate of 9.32% (p<0.01) than those 65-74 years (5.44%). Nationally the prevalence of OAB in rural zip codes was 6.01% vs 7.49% in urban zip codes. Among OAB patients only 21.4% were being treated with mirabegron or an antimuscarinic. Treatment rates are higher in females (29% vs 13% in males), Hispanics (29.5% vs 22% and 21% in Blacks and Whites, respectively) and older populations (23% in ≥75 years vs 19% in 65-74 years). CONCLUSIONS: The prevalence rates are similar to older estimates of Medicare data but are much lower than studies based on self-reporting. However, overall treatment rates of only 21% is in line with findings from other studies. These results also show substantial differences in OAB prevalence rates in particular patient demographics.