Familial hypercholesterolemia (FH), an inherited disorder of lipoprotein metabolism, is a risk for early cardiovascular disease (CVD). This autosomal dominant disease is characterized by markedly elevated plasma concentrations of low density lipoprotein (LDL) and total cholesterol (TC). The purpose of this study is to compare the effect of a diet low in saturated fats but enriched either with rapeseed oil (RO) or sunflower oil (SO) in children and adolescents with FH on serum lipoproteins.