This review article describes the types, pathophysiology, differential diagnosis and therapy of hypercholesterolemia. Special attention has been directed towards familiar hypercholesterolemia and familiar apolipoprotein B 100 defect. Clinically, both forms present very similar and may cause severe coronary arteriosclerosis and death before the age of 40 years. In the homozygote form CHD even develops prior to adolescence. With a frequency of 1:500 these forms of hypercholesterolemia are among the most common genetic disorders worldwide. The poor prognosis and their monogenetic dominant character emphasize the need for an exact distinction from the poligenetic forms of hypercholesterolemia and moreover underscore the necessity to screen for affected members in the family of already diagnosed cases and call for more aggressive therapeutic interventions. By dietary measures and monotherapy only 25% of patients reach the recommended cholesterol values. HMG-CoA reductase inhibitors proved to be the most effective. The remainders have to be treated with combinations of up to 3 lipid-lowering drugs. Alternative treatment such as extracorporal cholesterol elimination may become necessary.