Because of the original observation by Altschul et al., that nicotinic acid (niacin), not nicotinamide, in pharmacologic doses lowered human serum cholesterol levels, an avalanche of reports have been published over the past 45 years on the plasma lipid-regulating properties of this drug and its beneficial cardiovascular effects. A myriad of studies that have examined efficacy, safety, adverse effects, and pharmacologic properties of niacin rendered convincing evidence that niacin, used alone or combined with other agents, has favorable effects on serum lipoprotein regulation and on containment of atherothrombotic cardiovascular diseases. However, because of the unusual side effect profile of niacin and the availability of various formulations of this drug, niacin must be used prudently and with careful instruction and monitoring of patients. This review summarizes the pertinent and recent literature on niacin that impacts its therapeutic use. We also discuss some controversial issues and personal clinical experience and opinions on this topic.