Little is known about qualitative abnormalities of high-density lipoproteins (HDL) in systemic lupus erythematosus (SLE). We studied distribution and composition of HDL subclasses in 30 premenopausal women with uncomplicated SLE, and 18 controls matched for age and sex. Plasma and HDL lipids were determined by colorimetric enzymatic assays, HDL size distribution by native gradient polyacrylamide gel electrophoresis (PAGE) and apolipoproteins in HDL by sodium dodecyl sulphate denaturing PAGE. Compared with controls, SLE patients had significantly lower proportions of HDL(2b) (-14.7%) and higher proportions of HDL(3b) (+8.8%) and HDL(3c) (+23.3%). Cholesteryl ester (-18%) and apolipoprotein AI (-9%) were lower, whereas triglycerides (+32%) and apolipoprotein E (+27%) were higher in SLE HDL (P < 0.05; for all). In the whole population, stepwise regression analysis showed that only insulin concentrations (R(2) = 0.327) and plasma total apo AI (R(2) = 0.114) accounted independently to the variance in HDL size. This study shows that HDL distribution and composition are abnormal in non-complicated SLE patients. These HDL abnormalities have been reported to be associated to impaired atheroprotective properties of HDL and prevalence of coronary heart disease. Therefore, they may contribute to the premature atherosclerosis observed in young women with SLE.