Oxidised low-density lipoprotein (LDL) cholesterol is vasoconstrictor, mitogenic, pro-inflammatory and thrombogenic. This review summarises the evidence for its vasoconstrictor properties. LDL cholesterol potentiates noradrenaline vasoconstriction in the peripheral vasculature, and in the coronary, cerebral and renal vascular beds. There is also blunting of endothelium-dependent vasodilator responses to acetylcholine. These effects are reversed, or at least reduced, by lipid-lowering agents and (because LDL cholesterol down-regulates endothelial nitric oxide synthase) by the administration of L-arginine, the substrate for nitric oxide (NO) formation. Anti-oxidants also improve endothelial function in hypercholesterolaemic animals and human patients. More research is needed to assess the possible beneficial effects of lipid lowering on vascular structure and function, and on cardiovascular morbidity and mortality, in normocholesterolaemic individuals.