Consistent with earlier observations, Apoe−/− mice on the C57BL/6 background (B6-Apoe−/−) are more susceptible to atherosclerosis than 129-Apoe−/− at the root area, despite the lower plasma cholesterol levels in B6-Apoe−/− than in 129-Apoe−/−. This evidence concerns the gene APOE and atherosclerosis.