Psoriasis is characterized by defects in the normal cycle of epidermal development that lead to epidermal hyperproliferation, altered maturation of skin cells, vascular changes and inflammation. Also, psoriasis has been associated with an abnormal plasma lipid metabolism. Changes in plasma lipid and lipoprotein composition in patients with psoriasis may be the reason for the increased risk of atherosclerosis in these patients. We determined serum concentrations of lipids, lipoproteins and apolipoprotein Al and B (apo A1 and apo B) in 72 patients with psoriasis and 30 age matched controls. Serum lipoprotein (a) (Lp(a)), apo A1 and apo B were measured by immunoprecipitation assays, and the lipids and other biochemical parameters by enzymatic methods. Serum Lp(a) and triglyceride (TG) were significantly higher in patients with psoriasis than in healthy control subjects (p<0.01 for both). Apo B was also found to be higher in the patient group, but the difference was not significant. The levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and apo A1 did not differ significantly from those of the controls. These observations imply that serum Lp(a) and TG concentrations may play a role as risk factors for atherosclerotic disease in patients with psoriasis.