The functional properties of the apolipoproteins (apoB and apoA-I) governing lipoprotein metabolism make these variables conceptually important as markers for coronary artery disease risk. This aspect was examined in a biracial (black-white) population of children as part of the Bogalusa Heart Study. White children, especially boys, showed lower concentrations of apoA-I and ratios of cholesterol to apoB within low-density lipoprotein (LDL) than did black children. Persistence of apoB concentrations over time, coupled with its strong linkage with apoB gene locus, underscores the value of detecting apoB excess early in life. Further, the impact of apoE genotypes on apoB and apoA-I levels is already evident in childhood. We found that, as a screening test for detecting increased LDL cholesterol, apoB is superior to total cholesterol. Low values for apoA-I concentration, the apoA-I to apoB ratio, and LDL cholesterol to apoB ratio in children are strongly related to parental incidence of myocardial infarction; no such relationship is seen with respect to lipoprotein cholesterols. Thus, expanding screening strategies might be useful for identifying individuals with adverse apolipoprotein profiles early in life.