Obstructive sleep apnea syndrome (OSA) is a highly prevalent breathing disorder in sleep affecting at least 2-4% of the adult population. A large number of studies have demonstrated that OSA is an independent risk factor of cardiovascular morbidity and mortality. Sleep apnea was shown to be associated with hypertension, ischemic heart disease, stroke, pulmonary hypertension, cardiac arrhythmia, and cardiovascular mortality. The association of OSA with subclinical signs of cardiovascular morbidity such as endothelial dysfunction and vasculature remodeling on the one hand, and with oxidative stress, activation of inflammatory pathways and increased leukocytes/endothelial cells adhesion on the other, implicate that atherogenesis plays a major role in cardiovascular sequela of OSA. Results demonstrating that effective treatment of the syndrome can abort and even reverse the atherogenic process suggest that OSA should be diagnosed and treated as early as possible in order to prevent cardiovascular sequlea.