Thalassemia is a group of genetic disorders resulting from different mutations in the globin gene complex and leading to an imbalance in globin synthesis. Unmatched globin chains are less stable and susceptible to oxidation. Patients with beta-thalassemia/HbE are prone to increased oxidative stress as indicated by increased lipid peroxidation product, malondialdehyde (MDA), partly because of the presence of iron in the form of heme and hemichromes released from excess globin chains and excess iron deposition in various tissues. The level of antioxidant such as glutathione is markedly decreased while activities of antioxidant enzymes including superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) are increased. We have recently found that the levels of coenzyme Q(10) (CoQ(10)) are also very low in thalassemia. We therefore evaluated the oxidative stress and the antioxidants in these patients before and after supplementation with 100 mg CoQ(10) daily for 6 months. The results showed that the plasma level of CoQ(10) significantly increased and the oxidative stress decreased as the level of MDA declined. The administration of CoQ(10) led to significant improvement of biochemical parameters of antioxidant enzymes. The antioxidant supplementation will be beneficial for thalassemia patients as adjunct therapy to increase their quality of life.