The effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) versus omega-6 polyunsaturated fatty acid-rich safflower oil (control) on literacy and behavior in 90 children, aged 7-12 years, with attention-deficit/hyperactivity disorder (ADHD) were examined in a 4 month long, randomized, controlled trial. Subjects were randomly allocated supplements rich in EPA, DHA, or safflower oil. There were no significant differences between the supplement groups in the primary outcomes. However, the erythrocyte fatty acid profiles indicated that an increased proportion of DHA was associated with improved word reading and lower parent ratings of oppositional behavior. These effects were more evident in a subgroup of 17 children with learning difficulties and also included improved spelling, improved ability to divide attention, lower parent ratings of hyperactivity and restlessness. Results suggest that DHA, may improve literacy and behavior in children with ADHD, in particular for those who have comorbid learning difficulties.