Atherosclerotic coronary artery disease remains a major healthcare concern especially in developed countries. While lowering plasma cholesterol levels via diet, exercise, and pharmacotherapy can reduce this risk of developing coronary artery disease, there remains a need for more effective drug therapies. The azetidinone cholesterol absorption inhibitors typified by ezetimibe represent the first new approach to lipid lowering therapy in more than a decade. This review summarizes the medicinal chemistry of the azetidinone cholesterol absorption inhibitors as a class, with emphasis on factors that contributed both to the discovery of ezetimibe as well as to our overall understanding of S.A.R. trends in this area.