Endothelial dysfunction is an early sign of atherosclerosis. Patients with risk factors for atherosclerosis (e.g., hypertension, hyperlipidemia and diabetes mellitus) often show endothelial dysfunction at early stages of atherosclerosis before cardiovascular complications develop. Clinical studies and basic researches are revealing that calcium antagonists not only protect the endothelium through their hypotensive action but also improve the endothelial function through the stimulation of NO production. Regarding the mechanism for this kind of action by nifedipine (a calcium antagonist), it seems likely that the drug stimulates SOD expression in endothelial cells through enhanced VEGF expression by vascular smooth muscle cells, and thus reduces oxidative stress, leading to increased NO production.