Background: Hyperhomocysteinemia may constitute an independent risk factor for cardiovascular disease and may promote atherothrombosis. Psoriasis is one of the diseases associated with increased atherothrombosis. The aim of the present study was to examine serum total homocysteine (tHcy) level and its relationships with atherothrombotic markers. Methods: The study group included 30 patients with psoriasis (17 females and 13 males) with a mean age of 34.2 (age range: 27-40) and 30 sex and age matched healthy volunteers (15 females and 15 males) with a mean age of 36.7 (age range: 26-48). The concentrations of lipids, lipoproteins, acute phase reactants, tHcy and atherothrombotic markers [fibronectin, soluble vascular adhesion molecules-1 (sVCAM-1), soluble intercellular adhesion molecules-1 (sICAM-1), tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), autoantibodies against oxidized LDL (AuAb-oxLDL)] were determined. Results: The mean levels of serum tHcy, fibrinogen, fibronectin, sICAM, PAI-1 and AuAb-oxLDL were increased in patients whereas tPA, vitamin 1312 and folate levels were decreased significantly. Increased levels of sVCAM were not statistically significant. tHcy levels were negatively correlated with vitamin B-12 (r=-0.40, P=0.027) and positively correlated with PAI-1 and AuAb-oxLDL levels (r=0.46, P=0.011; r=0.39, P=0.035, respectively). Conclusions: It was concluded that the increased homocysteine concentration and altered endothelial cell-mediated proteins associated with increased lipids and LDL oxidation may play an important role for the development of atherothrombotic complications with psoriasis. (C) 2003 Elsevier Science B.V. All rights reserved.