Objective: To investigate effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on attention, literacy, and behavior in children with ADHD. Method: Ninety children were randomized to consume supplements high in EPA, DHA, or linoleic acid (control) for 4 months each in a crossover design. Erythrocyte fatty acids, attention, cognition, literacy, and Conners’ Parent Rating Scales (CPRS) were measured at 0, 4, 8, 12 months. Results: Fifty-three children completed the treatment. Outcome measures showed no significant differences between the three treatments. However, in children with blood samples (n = 76-46), increased erythrocyte EPA + DHA was associated with improved spelling (r = .365, p < .001) and attention (r = –.540, p < .001) and reduced oppositional behavior (r = –.301, p < .003), hyperactivity (r = –.310, p < .001), cognitive problems (r = –.326, p < .001), Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) hyperactivity (r = –.270, p = .002) and DSM-IV inattention (r = –.343, p < .001). Conclusion: Increasing erythrocyte DHA and EPA via dietary supplementation may improve behavior, attention, and literacy in children with ADHD. (J. of Att. Dis. XXXX; XX(X) XX-XX)