Background: NEDA is a composite measure that may ultimately influence clinical decisions concerning switches of disease modifying therapy (DMT) for relapsing remitting multiple sclerosis (RRMS) patients. Cohort studies from MS clinics suggest NEDA is not sustained over time in most patients despite DMT but may be limited by referral bias. We investigated NEDA in a population-based RRMS cohort. Methods: We identified all incident cases of RRMS in Olmsted County from 01/01/2000-12/31/2011. Retrospective chart review was conducted to determine persistence of NEDA -following RRMS diagnosis. NEDA failure was defined as new MRI activity, relapse, or expanded disability status scale (EDSS) -worsening. Results: There were 93 incident cases of RRMS with 82 individuals having sufficient follow-up to determine persistence of NEDA. Prior to NEDA failure 44 were not on DMT, 37 were on first-tier, injectable DMT, and 1 received mitoxantrone. NEDA was maintained by 63% at 1 year, 38% at 2 years, 19% at 5 years, and 12% at 10 years. Disability measured by EDSS was no different at 10 years in patients maintaining NEDA versus those that failed NEDA at one year (p=0.3). Conclusions: Maintenance of NEDA beyond 2 years is infrequent among a population-based cohort of newly diagnosed RRMS patients and similar to prior clinic-based cohorts.