Dyslipidemia may contribute to atherosclerosis in hemodialysis patients. While hypertriglyceridemia is relatively common in this population, hypercholesterolemia is not. Since abnormalities in various plasma cholesterol fractions and lipoproteins have been associated with an increased incidence of cardiovascular disease in the nonuremic population, we examined these abnormalities to determine whether they occur in patients with chronic renal failure. Twenty-four patients on maintenance hemodialysis were studied. We found that, despite relatively low plasma total cholesterol levels, a substantial number of patients had low high-density lipoprotein cholesterol, low apolipoprotein AI, and high apolipoprotein B levels. Furthermore, approximately 40% and 30%, respectively, of the patients had elevated plasma levels of lipoprotein(a) and remnants of chylomicron and very low-density lipoprotein. Lipoprotein(a) levels could not be predicted from any of the variables that were studied. The abnormal plasma levels of these potentially atherogenic lipids and lipoproteins suggest that they may contribute to the high incidence of cardiovascular diseases in the hemodialysis population.