Background: The involvement of oxidative stress in the pathogenesis of various skin diseases has been suggested. Objective: Urinary malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) levels served as indices of oxidative stress. We explored whether MDA and 8-OHdG levels were higher in patients with atopic dermatitis (AD) than in healthy controls. In addition, we evaluated the optimal cut-off values for 8-OHdG and MDA in the diagnosis of AD. We explored the associations between AD severity and the levels of serum IgE and oxidative products. Methods: Urine samples were obtained from 52 AD patients and 27 healthy controls. We measured MDA levels (reflecting lipid oxidation) and 8-OHdG levels (reflecting DNA oxidation). Disease severity was assessed using the Scoring of Atopic Dermatitis (SCORAD) index. Results: The urinary 8-OHdG level was 208.37±145.39 ng/mg Cr in AD patients and 115.65±63.95 ng/mg Cr in healthy controls. The urinary MDA level was 2.92±1.06 mmol/mg Cr in AD patients and 2.20±0.54 mmol/mg Cr in healthy controls. Both the urinary 8-OHdG and MDA levels were significantly higher in AD patients than in healthy controls (p=0.007, p=0.001, respectively). However, we found no correlation between disease severity or serum IgE and oxidative product levels. Levels of oxidative products did not differ significantly between children and adolescents and adults, males and females, or patients with intrinsic or extrinsic AD. Conclusion: MDA and 8-OHdG levels were higher in AD patients than in healthy controls. Oxidative stress may be involved in the pathophysiology of the disease. (Korean J Dermatol 2019;57(8):457∼463)