Apolipoprotein E phenotypes and gene frequencies were determined in 560 patients receiving long-term hemodialysis. In addition, fasting plasma lipid- and apolipoprotein-concentrations were evaluated in 245 of these individuals. The distribution of the three major apolipoprotein E alleles (epsilon 4, epsilon 3, and epsilon 2) and that of the six common apolipoprotein E phenotypes (E4/4, E3/3, E2/2, E4/2, E4/3, and E3/2) in the dialysis group was nearly identical to that of healthy controls. Patients with the apolipoprotein E phenotypes E2/2, E4/4 and E4/3 (comprising 24% of the whole group) had higher mean plasma cholesterol- and triglyceride-concentrations than those with the apolipoprotein E phenotypes E3/3 and E3/2 (72% of the whole group). Thus, the genetic polymorphism of apolipoprotein E may contribute to the individual risk of accelerated atherosclerosis in patients under maintenance hemodialysis.