Elevated levels of high-density lipoprotein cholesterol (C-HDL) can explain apparent hypercholesterolemia in some children, and high C-HDL levels may aggregate in families. In this study, 17 kindreds were identified by virture of hypercholesterolemic proband children whose hypercholesterolemia was accounted for the elevated C-HDL levels Family lipod and lipoprotein sampling revealed three-generation vertical appearance of elevated C-HDL level in two kindreds, and two-generation vertical appearance in eight additional kindreds. Since CHDL level is inversely associated with coronary heart disease in adults, it is important to quantitate C-HDL and low-density lipoprotein cholesterol (C-LDL) in hypercholesterolemic children and to identify those with putatively reduced risk (elevated C-HDL level) or increased risk (elevated C-LDL level).