Using data and blood samples from the 75 nuclear families of Nancy, a determination was made of the effects of apolipoprotein B and E genes on fasting levels of total cholesterol and triglycerides, LDL-cholesterol, HDL-cholesterol, HDL2-cholesterol, HDL3-cholesterol, apo A-I, apo-B, apo C-III, and apo-E. Genetic variability was directly assessed by DNA restriction site variability in the apolipoprotein B gene and by measuring the apolipoprotein E polymorphism. Data collected from these families permitted the partitioning of the effects of the apolipoprotein B and E genes from the overall polygenetic and phenotypic variance of the measured lipids, lipoproteins, and apolipoproteins.