Oxidative stress occurs when there is excessive free-radical production or a low antioxidant level. The role of free radicals in the pathogenesis and in the progression of many diseases has often been discussed, but it has not been widely investigated in leishmaniasis. However, measurement of oxidants and antioxidants in the serum seems to be of great value. In this study, we aimed to determine lipid peroxidation levels as markers of oxidative stress in the serum of patients suffering from cutaneous leishmaniasis, which is a common health problem in our region of Southern Anatolia, Turkey. Forty patients aged between 5-50 years and forty controls aged between 5-50 years were included in the study. The LPO levels of the patients with active cutaneous leishmaniasis were significantly higher (p<0.001) than those of healthy controls. As a result, it is possible to conclude that patients with cutaneous leishmaniasis are affected by oxidative stress, which may contribute to the progression of the disease.