OBJECTIVE: Rest is a widely recommended treatment for concussion, but its utility is unclear following the acute stage of recovery. This study examined the effects of 1-week of prescribed rest in concussed adolescent athletes. METHOD: Participants were 13 adolescent athletes with persistent symptoms following a concussion. More than three-quarters (77%) had self-reported ADHD, learning disability or two prior concussions. All completed ImPACT at another facility, but none completed a period of comprehensive rest prior to examination at a specialty practice. Three time points of test data were compared, to control for possible spontaneous recovery: Test 1 (external facility), Test 2 (before prescribed rest) and Test 3 (following prescribed rest). RESULTS: Repeated measures ANOVAs revealed a significant effect of prescribed rest on all ImPACT composite scores and the total symptom score. Post-hoc analyses revealed no significant differences between Time 1 and Time 2, whereas significant differences were present after prescribed rest. Following prescribed rest, having two or more reliably improved cognitive test scores or having improved symptoms was present in eight of the 13 patients (61.5%). CONCLUSIONS: A substantial percentage of adolescents with persistent symptoms following concussion showed improvement in symptoms and cognitive functioning following education, reassurance and 1-week of prescribed rest.