Although xanthoma formation commonly accompanies hyperlipidemias, the exact relationship between these two manifestations is not clear and appears to differ significantly in various hereditary or acquired conditions. Over the past 12 years, we have studied in Lebanon 52 patients presenting withjuvenile xanthomatosis, marked hypercholesterolemia and hyperbetalipoproteinemia and evidence of rapidly developing atherosclerosis [4-7]. These patients fulfill the presently accepted criteria for the homozygous form of familial hypercholesterolemia (FH)[4] or familial type II hyperbetalipo-proteinemia [1].