Nicotinic acid, a vitamin of the B complex (B3), is the most potent high-density lipoprotein cholesterol (HDL-C) raising agent currently available, when used at pharmacological doses. In randomized intervention trials, nicotinic acid has been shown to lower the risk of coronary heart disease and to slow the progression of coronary artery lesions. Niacin lowers plasma triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) levels, in addition to raising HDL-C. The mechanism by which nicotinic acid increases plasma HDL cholesterol levels is not clear. In studies conducted in normolipidemic subjects, niacin increased HDL-C by reducing its plasma clearance. In a placebo-controlled, randomized, crossover study conducted in dyslipidemic subjects, nicotinic acid increased plasma HDL-C levels by increasing the production rate of apo A-I, the major protein in HDL, and the cholesterol content in HDL. Further studies need to assess the role of niacin on HDL metabolism in subjects with elevated plasma TG and low HDL-C levels.