Background: Psoriasis is a common chronic and recurrent inflammatory skin disease that can occur due to abnormalities in essential fatty acid metabolism, lymphokine secretion, free radical generation, lipid peroxidation and eicosanoid metabolism, and has been associated with increased frequency of cardiovascular events. The current study was designed to evaluate plasma lipids, susceptibility of LDL to oxidation and oxidant-antioxidant status and their relationships in patients with psoriasis. Methods: The study group included 35 patients with psoriasis (18 females and 17 males), and 35 sex- and age-matched healthy volunteers (16 females and 19 males). From blood samples, their lipids, lipoproteins, acute phase reactants, lipid peroxidation products [lipid hydroperoxide (LHP) and malondialdehyde (MDA)], antioxidant enzymes [glutathione peroxidase (GSH-Px), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT)], total antioxidant status (TAS) and autoantibodies against oxidized low-density lipoprotein (AuAb-oxLDL) levels were determined. Moreover, the susceptibility of copper-induced in vitro oxidation of LDL was examined. Results: The mean levels of atherogenic lipids (total cholesterol [TC], triacylglycerol [TG] and LDL cholesterol [LDL-C]), acute-phase reactants (CRP, ESR, PMNLs, ceruloplasmin and fibrinogen) and lipid peroxidation products, AuAb-oxLDL levels in patients with psoriasis were found to be significantly higher than those of healthy subjects. On the other hand, TAS and antioxidant enzyme activities (CAT, SOD and GSH-Px in erythrocyte and SOD in plasma) were significantly lower when compared to healthy subjects. The lag times [t(lag)], a measure of resistance to oxidation of LDL, were also lower. The levels of AuAb-oxLDL in patients were correlated with TC, LDL-C, plasma LHP, erythrocyte MDA, oxidized LDL-MDA (oxLDL-MDA), fibrinogen, CRP, PMNL levels and plasma SOD activities (r = 0.69, P < 0.01; r = 0.64, P < 0.01; r = 0.38, P < 0.05; r = 0.65, P < 0.01; r = 0.34, P < 0.05; r = 0.34, P < 0.05; r = 0.53, P < 0.01, r = 0.34, P < 0.05; r = -0.67, P < 0.01, respectively). On the other hand, t(lag) was correlated negatively with the levels of VLDL-TG, VLDL-TC and LDL-TG but positively correlated with the levels of TAS in psoriatics (r = -0.49, P < 0.01; r = -0.49, P < 0.01, r = -0.65, P < 0.05; r = 0.37, P < 0.05). Conclusions: It was concluded that the psoriatic patients could be considered as a group with an increased atherosclerotic risk because of increased oxidant stress, decreased antioxidant capacity and susceptibility in lipid profile and lipoprotein content to atherogenicity. (C) 2002 Elsevier Science B.V All rights reserved.