Alopecia areata (AA) is an autoimmune inflammatory disease. However, little is known about the alterations in lipid peroxidation and antioxidant enzymes in the scalp of patients with AA. Therefore, the aim of this study was to investigate the status of oxidative stress in the scalp of patients with AA. We measured the levels of thiobarbituric acid reactive substances (TBARS) as lipid peroxidation status, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) as antioxidant enzymes in the scalp of ten patients with AA and ten control subjects. The levels of TBARS in scalp of patients with AA (3654.1+/-621.2 nmol/g tissue) were significantly higher than those of controls (1210.2+/-188.8 nmol/g tissue) (P=0.002). The levels of SOD (134.8+/-23.8 U/g tissue) and GSH-Px (332.7+/-66.2 U/g tissue) in scalp of patients with AA were also significantly higher than those of controls (63.2+/-8.8 U/g tissue, 112.0+/-18.4 U/g tissue, respectively) (P=0.019, P=0.002, respectively). The mean levels of TBARS, SOD and GSH-Px in early phase of disease were increased 2-fold as compared with late phase of the disease. These results indicate that oxidative status is affected in AA. Lipid peroxidation and antioxidant enzymes may be involved in the pathogenesis of AA. Furthermore, we found high SOD and GSH-Px activities in the scalp of patient with AA. These high levels could not protect the patients against the reactive oxygen species, because lipid peroxidation could not be lowered in AA patients.