BACKGROUND soriasis is a chronic, immune-mediated, inflammatory disease. Previous studies have indicated a possible role of oxidative stress in the pathogenesis of psoriasis. OBJECTIVE We sought to compare special oxidative stress and antioxidant markers in psoriatic patients. METHODS This study included 35 patients with psoriasis and 35 healthy controls. Serum levels of oxidant markers, including advanced glycation end products (AGEs) and advanced oxidation protein products (AOPPs), as well as antioxidant enzymes, including lecithin-cholesterol acyltransferase (LCAT), paraoxonase-1 (PON1), and ferric-reducing ability of plasma (FRAP), were measured. RESULTS The mean age of the subjects was 39.63±13 years in the case group and 39.37±12.62 years in the control group (p=0.92). The mean Psoriasis Area and Severity Index (PASI) scores of these groups were 15.27 and 10.47. The mean levels of fasting blood sugar and C-reactive protein were significantly higher in the case group than the control group (p=0.04 and p=0.02, respectively). Moreover, the mean levels of AGEs and AOPPs in the case group were significantly higher than in the control group (p=0.001), while the mean levels of FRAP, PON1, and LCAT were significantly lower in the case group than in the control group (p=0.001). There was no significant association between PASI and oxidant or antioxidant markers, except for AOPP, which had a negative association with PASI. CONCLUSIONS Our findings suggest an imbalance among oxidative stress and antioxidant markers in the pathogenesis of psoriasis. The oxidant-antioxidant enzymatic system is impaired in psoriasis as a result of increased oxidant products and reduced antioxidant activity.