OBJECTIVE:To compare long-term outcome of children and young adults with arterial ischemic stroke (AIS) from 2 large registries. METHODS:Prospective cohort study comparing functional and psychosocial long-term outcome (≥2 years after AIS) in patients who had AIS during childhood (1 month–16 years) or young adulthood (16.1–45 years) between January 2000 and December 2008, who consented to follow-up. Data of children were collected prospectively in the Swiss Neuropediatric Stroke Registry, young adults in the Bernese stroke database. RESULTS:Follow-up information was available in 95/116 children and 154/187 young adults. Median follow-up of survivors was 6.9 years (interquartile range 4.7–9.4) and did not differ between the groups (p = 0.122). Long-term functional outcome was similar (p = 0.896)53 (56%) children and 84 (55%) young adults had a favorable outcome (modified Rankin Scale 0–1). Mortality in children was 14% (13/95) and in young adults 7% (11/154) (p = 0.121) and recurrence rate did not differ (p = 0.759). Overall psychosocial impairment and quality of life did not differ, except for more behavioral problems among children (13% vs 5%, p = 0.040) and more frequent reports of an impact of AIS on everyday life among adults (27% vs 64%, p < 0.001). In a multivariate regression analysis, low Pediatric NIH Stroke Scale/NIH Stroke Scale score was the most important predictor of favorable outcome (p < 0.001). CONCLUSION:There were no major differences in long-term outcome after AIS in children and young adults for mortality, disability, quality of life, psychological, or social variables.