AbstractThe apparent direct casual relationship of elevated blood lipids to the pathogenesis of atherosclerosis has resulted in many lines of investigation directed toward the control of lipids, particularly cholesterol, in blood and tissues. Much of this work during the past decade has been concerned with the regulation of endogenous synthesis of cholesterol. No attempt has been made herein to discuss the many cholesterol synthesis inhibitors which have been reported, but rather the salient features of two compounds, triparanol and nicotinic acid, both of which have been extensively used in the clinic, have been reviewed with a major emphasis on their mechanism of action. In addition, preliminary studies with two classes of azasteroids, a group of 3‐(ॆ‐dialkylaminoethoxy)‐substituted steroids, and a substituted alphatic acid, ethyl‐ॅ‐p‐chlorophenoxyisobutyrate, have been discussed. Brief mention is made of the effect of another class of hypocholesterolemic drugs, D‐ and L‐triiodothyronine, on the synthesis of chenodeoxycholate and cholate from cholesterol.