Background: Change of lipids and lipoprotein metabolism and an imbalance of the oxidant-antioxidant system related to the disease activity have been reported in Behcet's disease. Therefore, there is a tendency of oxidative modification of lipids and lipoproteins in patients with the disease. Objective: To investigate serum autoantibodies against oxidatively modified low-density lipoprotein (oxLDL) as a marker for the degree of in vivo oxidation of lipoproteins in Behcet's disease. Methods: Serum autoantibodies against oxLDL, total cholesterol, triacylglycerol, HDL cholesterol, LDL cholesterol, apolipoprotein (Apo) Al, Apo B, alpha(1)-antitrypsin, alpha(2)-macroglobulin and erythrocyte sedimentation rate were determined in 37 patients and 30 sex- and age-matched healthy volunteers. Autoantibodies against oxLDL were measured by a commercial enzyme-linked immunosorbent assay. Results: Serum autoantibody levels against oxLDL were significantly higher in patients than in controls (425 +/- 365 and 187 +/- 132 mU/ml, respectively; p < 0.05). The levels of autoantibodies against oxLDL in the patients were found to correlate with total cholesterol, LDL cholesterol, HDL cholesterol and al-antitrypsin levels (r = 0.38, p < 0.05; r = 0.42, p < 0.05; r = -0.38, p < 0.05; r = 0.42, p < 0.05, respectively). Conclusion: It has been shown in previous studies that high autoantibody titers against oxLDL may be important in diseases with atherosclerosis as seen in systemic lupus erythematosus and rheumatoid arthritis. High autoantibody titers against oxLDL are not specific for Behcet's disease but probably important for pathologic processes in the disease. We suggest that increased levels of autoantibodies against oxLDL may be a factor responsible for endothelial dysfunction and development of vascular pathology in Behcet's disease.