Hyperlipidemia is a risk factor for the development of coronary heart disease. Many patients decline prescription lipid-lowering agents and opt instead for supplements. Before any supplement can be routinely recommended it is crucial to examine the types of clinical trials that have been performed, the mechanism by which a supplement is felt to alter lipids, the population studied, potential adverse effects, and the possibility that investigators might be biased. Clinical trial evidence strongly supports the notion that both red yeast rice and plant stanols and sterols effectively lower low-density lipoprotein (LDL) cholesterol. Preliminary evidence supports the possibility that green tea catechins and black tea theaflavins may lower LDL. Data do not support an LDL-lowering claim for guggulipid, policosanol, or cinnamon. Finally, there is strong clinical trial evidence suggesting that marine omega-3 fatty acids lower triglycerides.