Oxygen radicals are key molecules in the pathogenesis of various infectious diseases. To investigate whether oxidative stress increases in measles or not, plasma malondialdehyde (MDA) levels, serum carbonyl levels and plasma total sulphydryl levels were measured in 25 measles patients and 25 healthy controls by using spectrophotometry. Plasma MDA and serum carbonyl levels in patients with measles were detected higher than those in the control group. Plasma sulphydryl levels were found to be lower in the patient group when compared with the control group. It is concluded that oxidative stress increases in measles and antioxidant agents can be beneficial in the treatment.