Autism is a neurodevelopmental disability with an increasing prevalence. Traditional medicine does not offer any cures for autism; thus, many parents of children with autism are attracted to complementary and alternative therapies, one of which is dietary supplementation with the long chain polyunsaturated omega-3 fatty acid, docosahexaenoic acid (DHA). DHA is a critical structural lipid of brain cell membranes and differences in brain DHA content may influence synaptic function, particularly in nutritionally-sensitive areas of the brain, such as the cerebellum and hippocampus, which may be brain structures involved in the etiology of autism. This study is a randomized, double-blind, placebo-controlled trial investigating whether DHA supplementation is an effective treatment for children with autism. Eighty children with autism will be randomized to receive 200mg of DHA or placebo for 6 months. Outcome variables will include total plasma fatty acid patterns and scores on parent and investigator-completed behavioral and developmental rating scales at baseline and after 3 and 6 months of supplementation. Differences between groups after 6 months will be evaluated using regression methods. Regression analysis will be used to detect correlations between plasma total fatty acid DHA contents and scores on the various outcome measures. Results from this study will either provide evidence for a breakthrough biomedical treatment alternative for children with autism or evidenced-based advice to desperate parents in regard to their choices of potential treatments for their children with autism