Despite the huge health and economic burden of migraine headache, few medications have been approved for its prophylactic treatment, most of which can potentially induce serious adverse effects. Coenzyme Q10 (CoQ10) is a supplement and has shown preliminary benefits in migraine prophylaxis. We aimed to assess this effect in an adult population. This is an open-label, parallel, add-on, match-controlled trial. Eighty patients diagnosed with migraine headache based on International Headache Society criteria were allocated to receiving only their current preventive drugs or their current preventive drugs plus 100 mg CoQ10 daily, matching for their baseline characteristics, and were assessed for frequency and severity of attacks, and >= 50 % reduction in attack frequency per month. Thirty-six and 37 patients were analyzed in CoQ10 and control groups, respectively. Number of attacks per month dropped significantly in the CoQ10 group (mean decrease: 1.6 vs. 0.5 among CoQ10 and control groups, respectively, p < 0.001). A significant reduction was also evident in the severity of headaches (mean decrease: 2.3 vs. 0.6 among CoQ10 and control groups, respectively, p= 50 % reduction in the frequency of attacks per month, the number needed to treat was calculated as 1.6. No side effects for CoQ10 were observed. This study suggests that CoQ10 might reduce the frequency of headaches, and may also make them shorter in duration, and less severe, with a favorable safety profile.