In homozygous LDLR-deficient (Ldlr−/−) hamsters on a normal diet, the plasma cholesterol levels could reach over 600 mg/dL and develop more severe atherosclerotic lesions than Ldlr−/− mice and rats on a normal diet, while a 12-week HFHC diet results in severe hypercholesterolemia in Ldlr−/− hamsters (4997 ± 233 mg/dL), significantly higher than in heterozygous (Ldlr+/−) hamsters (2081 ± 161 mg/dL). This evidence concerns the gene LDLR and familial hypercholesterolemia.