OBJECTIVE: The purpose of the present study was to evaluate the efficacy of omega-3 and Korean red ginseng on improving attention deficit hyperactivity disorder (ADHD) symptoms and cognitive function in children with ADHD. METHODS: A total of 40 children aged 6 to 12 years diagnosed with ADHD participated in this open-label trial. Participants received daily supplements containing 500 mg of omega-3 (eicosapentaenoic acid, 294 mg; docosahexaenoic acid, 206 mg) and 3 mg of Korean red ginseng extract (combination of ginsenoside Rg1, Rb1, and Rg3) for 12 weeks. No psychotropic drug was allowed during the study period. ADHD symptoms were assessed using the ADHD Rating Scale (ADHD-RS) and Clinical Global Impression-Severity (CGI-S) scale. Neuropsychological tests on sustained attention, short-term memory, and executive function were also assessed. RESULTS: After 12 weeks, participants showed significant improvements on ADHD-RS (31.12 +/- 8.82 at baseline, 24.15 +/- 11.45 at endpoint; p < 0.001) and CGI-S (3.38 +/- 1.18 at baseline, 2.94 +/- 1.00 at endpoint; p < 0.001). On the Continuous Performance Test, commission errors significantly decreased, while reaction time significantly increased. Immediate recall and delayed recall on both Auditory Verbal Learning Test and Complex Figure Test showed significant improvements. Scores of Color-Word Task from Stroop Color-Word Test also showed significant improvements after the treatment. The supplement was well tolerated. CONCLUSION: The results of this pilot study suggest that the combination of omega-3 and Korean red ginseng may improve ADHD symptoms and cognitive function including attention, memory, and executive function in children with ADHD. Future randomized placebo-controlled trials with a larger sample is warranted.