Seborrheic dermatitis (SD) is a common, chronic inflammatory skin disease that mainly affects the scalp. The objective of this study was to evaluate the activities of superoxide dismutase (SOD) and catalase (CAT) and the levels of malondialdehyde (MDA) in scraping samples of patients with scalp SD. Thirty consecutive patients with a diagnosis of scalp SD and thirty-one healthy volunteers were enrolled. The samples were obtained by scraping the skin surface of the scalp. SOD and CAT activities and MDA levels were measured in scraping samples by spectrophotometric method. SOD and CAT activities and MDA levels were significantly higher in patients than in controls (p<0.001 all). There was a positive correlation between the severity of the disease and itching scores (contingency coefficient = 0.671, p<0.001). Except for this correlation, there was no significant correlation among age, sex, duration and severity of the disease, itching scores, antioxidant enzymes and MDA levels in the patient group (p>0.05). Cutaneous oxidative stress in patients with SD may play an important role in the pathogenesis of the disease. Further clinical and laboratory evaluation of the oxidant/antioxidant system in patients with SD is warranted.