Hypercholesterolemia is a major risk factor for atherosclerosis, and lowering cholesterol can significantly reduce the risk for cardiovascular diseases. Oxidation of LDL has recently been recognized as playing an important role in the initiation and progression of atherosclerosis. Oxidized LDL, but not native LDL, promotes vascular dysfunction by exerting direct cytotoxicity to endothelial cells, by increasing chemotactic properties of monocytes, by transforming macrophages to foam cells, and by enhancing the proliferation of endothelial cells, monocytes, and muscle cells. All these events are recognized as contributors to cardiovascular diseases. This paper presents experimental evidence showing that several garlic compounds can suppress LDL oxidation in vitro. Short-term supplementation of garlic in human subjects has demonstrated an increased resistance of LDL to oxidation. These data suggest that suppressed LDL oxidation may be one of the mechanisms that accounts for the beneficial effects of garlic in cardiovascular health.