Abstract: "Observations on the metabolism of chyle cholesterol in the rat show that exogenous cholesterol entering the systemic circulation in chyle exists in lipoproteins of low density (including chylomicrons) migrating with a high Sf rate (i.e.>400) in the ultracentrifuge. Following entry into the systemic circulation these molecules are rapidly removed from the plasma. This "clearing" of serum chyle cholesterol is a tissue phenomenon, the liver being the predominant site. Within the liver the chyle cholesterol esters are at least partially hydrolyzed; hydrolysis apparently does not occur in the plasma to any appreciable extent. After its entry into the liver exogenous cholesterol, if normally metabolized, presumably mixes with and becomes indistinguishable from cholesterol produced by endogenous synthesis."