Biometrical genetic studies have established that a significant proportion of the fasting plasma lipid, lipoprotein, and apolipoprotein levels is attributable to genetic differences among individuals. Although these studies indicate that polygenetic variability is contributing, they do not yield information about specific candidate genes whose products are involved in the metabolism of the phenotype of interest. Recent advances in molecular biology enable one to measure genetic variability at candidate loci for several risk factors for the common chronic diseases. With this information the contribution of specific candidate genes to polygenetic and phenotypic variability can be estimated. Estimating the effects of specific candidate loci will facilitate the investigation of the interaction between genetic and environmental factors. This study focussed on restriction fragment length polymorphisms in and around the apolipoprotein B gene and on the apolipoprotein E protein polymorphism. The apolipoprotein B and apolipoprotein E genes were selected because of their central role in lipid metabolism and interaction with dietary factors.