Cholesteryl ester transfer protein (CETP) catalyzes the transfer of cholesteryl ester from high-density lipoprotein (HDL) to apolipoprotein B-containing lipoproteins in exchange for triglyceride, and thereby plays a major role in lipoprotein metabolism. The reciprocal increase in HDL cholesterol (HDL-C) and decrease in low-density lipoprotein cholesterol (LDL-C) associated with CETP deficiency has led to the search for synthetic CETP inhibitors over the past 15 years. Several potent inhibitors have been identified, two of which--JTT-705 and torcetrapib--are undergoing clinical trials. Recent reports that torcetrapib is able to simultaneously raise HDL-C twofold and lower LDL-C by < or = 42% has heightened interest in this new class of agents. Upcoming results from Phase III trials of torcetrapib should provide anatomical measurements of atherosclerosis and thus the first assessment of therapeutic benefit.