Cholesterol is distributed in different body pools, Input in these pools takes place through absorption of dietary cholesterol and endogenous synthesis. Absorption is limited in man. Endogenous synthesis is under negative feedback control, but its physiological relevance in man is less well established. Recent studies in familial hypercholesterolemia have shown a slower catabolism of low density lipoproteins (LDL) and an overproduction of apoprotein B. It seems that also the synthesis of the apoprotein B is controlled by a feedback mechanism. Overall concentration of lipids and lipoproteins in plasma is determined by the interaction between several genetic and dietary feedback mechanisms.