This chapter reviews the impact of continuous positive airway pressure (CPAP) therapy on major treatable risk factors for cerebrovascular atherosclerotic disease, including arterial hypertension, diabetes mellitus, and dyslipidemia. As atrial fibrillation (AF) is recognized as an important risk factor for thromboembolic cerebrovascular disease, the chapter also discusses the effect of CPAP treatment on AF. The effect of CPAP on systemic blood pressure in patients with obstructive sleep apnea syndrome (OSAS) seems to depend on the severity of sleep-disordered breathing, daytime sleepiness, extent of obesity, and the hours of nightly CPAP use. OSA and type 2 diabetes are both conditions that are closely associated with obesity, with a high prevalence of OSA in those patients with type 2 diabetes. Preliminary evidence from general and OSA population cohorts show that OSA precedes stroke and may therefore contribute to the development of stroke.