Despite media and public expectation of efficacy, no study to date has investigated the cognitive and mood effects of omega l supplementation in healthy children. This randomised, double-blind, placebo-controlled, parallel groups pilot study assessed the cognitive and mood effects of either 400 mg or 1000 mg of docosahexaenoic acid a (DHA) in si healthy children aged 10-12 years. Cognitive performance and mood was assessed prior toe and 8 weeks following, commencement of treatment. There was a significant treatment effect on one cognitive measure a speed of word recognition),, with the lower dose speeding, and the higher dose slowing, performance. Overall, the pattern of results strongly suggests that this effect was due to chance fluctuations in performance and that the treatments had no consistent or interpretable effect on performance. The results here do not suggest that supplementation with these doses of DHA for 8 weeks has any beneficial effect on brain function in cognitively intact children.