The goal of this open-label trial was to examine the efficacy and safety of a 12-week omega-3 fatty acids supplementation among children suffering with Autism Spectrum Disorders (ASD). A total of 41 children and adolescents aged 7-18 years (36 boys, 5 girls; mean age = 11.66, s.d. = 3.05) diagnosed with ASD participated in the study. At post-treatment, participants showed significant improvements on all subscales of the Social Responsiveness Scale (P < 0.01) and the Social and Attention Problems syndrome scales of the Child Behavior Checklist (P < 0.05). Blood fatty acid levels were significantly correlated with changes in the core symptoms of ASD. Baseline levels of blood fatty acid levels were also predictive of response to the omega-3 treatment. Omega-3 fatty acids supplementation was well-tolerated and did not cause any serious side effects. Our findings lend some preliminary support for the use of omega-3 fatty acids supplementation in addressing ASD. Future randomized controlled trials of omega-3 fatty acids in ASD with blood fatty acid measurements with a larger sample and longer follow-up period is warranted.