AbstractReduced levels of glutathione peroxidase (GSH‐Px) have been observed in adults with asthma. This study examines the antioxidant status in children with asthma compared with a control group in a cross‐sectional analysis. Red blood cell GSH‐Px, superoxide dismutase (SOD), and plasma concentrations of retinol, vitamin C, alpha tocopherol, and cholesterol were measured in 37 subjects (26 males) with stable controlled asthma. Thirty‐five subjects (20 males) without eczema, hayfever, or recurrent respiratory symptoms were used as a control group. Children with asthma had significantly reduced red blood cell GSH‐Px activity compared with controls [median (inter‐quartile range) for asthma group, 10.25 (9.25–11.91)]; for control group, 11.75 (10.34–12.26) IU/g Hb; P = 0.0061. There were no significant differences in activity of SOD or vitamin C, retinol, or alpha tocopherol/cholesterol ratio. The reduction in GSH‐Px activity may have therapeutic and etiological implications for asthma. The effects of disease activity and treatment on antioxidant status needs for further study. Pediatr Pulmonol. 1994; 18:34–38. © 1994 Wiley‐Liss. Inc.