Essential fatty acids (EFA) are needed for normal sensory, cognitive, and motor function. The EFA blood profile seems to be different in children with attention-deficit/hyperactivity disorder (ADHD) as compared to matched controls. Previous open EFA supplementation trials were successful in demonstrating significant therapeutic effects in this population, whereas most of the randomized controlled trials failed to show any benefit over placebo. The current randomized, double-blind, placebo-controlled trial tested the influence of short-chain EFA supplementation on ADHD children, using parent and teacher questionnaires and a computerized continuous performance test. A total of 73 unmedicated children aged 7-13 years with a diagnosis of ADHD participated in the study; 63 children completed the study. The EFA supplement contained 480 mg of linoleic acid and 120 mg of alpha-linolenic acid, and the placebo contained 1000 mg of vitamin C (daily amounts); both were given for a 7-week supplementation period. Analysis of variance for repeated measures revealed that both treatments ameliorated some of the symptoms, but no significant differences were found between the groups in any of the treatment effects.