Atherosclerosis is the major public health problem in much of the world today. The information summarized in this review, based on the recognized apolipoprotein structural variants appreciated at both the protein and gene levels, indicates that apolipoprotein genetic variation plays a major role in determining human genetic susceptibility to this disease. With the use of cloned apolipoprotein genes, it should, in the near future, be possible to determine how their expression is regulated; this should provide insight into other classes of mutations of a regulatory nature that might have clinical significance. In addition, the many association and linkage studies currently being undertaken will provide the rationale for cloning defective alleles and determining specific causative mutations. Both structural and regulatory mutations can then be described either with restriction enzymes and Southern blotting or by direct oligonucleotide hybridization techniques in the general population. This will allow the identification of presymptomatic atherosclerosis-susceptible individuals who would be targets for primary preventative therapy.