1) The study investigated the redox status of patients with alpha-thalassemia trait and hemoglobin H (Hb H) disease. 2) Lipid peroxidation, as measured by plasma TBARS levels, was increased in alpha-thalassemic patients and highest in Hb H patients. 3) Plasma levels of vitamins A, C and E were significantly lower in alpha-thalassemic patients compared to controls. The overall antioxidant capacity correlated inversely with the severity of the alpha-globin gene defect.