Obstructive sleep apnoea (OSA) is a common disorder, in which loss of pharyngeal dilator muscle tone during sleep causes recurrent collapse of the upper airway and temporary cessation of breathing. Repeated apneas and hypopneas lead to cycles of intermittent hypoxia/hypercapnia, increased negative intrathoracic pressure and arousals from sleep. These consequences of OSA are associated with a cascade of cardiovascular and neurohumoral consequences, including sympathetic nervous system hyperactivity, raised heart rate variability, increases in blood pressure, myocardial wall stress, oxidative stress, systemic inflammation, platelet aggregation and impaired vascular endothelial function, which contribute, in turn, to increased cardiovascular risk and, in particular, to the development of chronic systemic arterial hypertension and arrhythmias, especially atrial fibrillation (AF). Given that the prevalence of OSA is modified by age and gender, OSA-related cardiovascular diseases may also be affected by the same factors. This review focuses on the potential role of OSA in systemic arterial hypertension and AF, and discusses the most interesting studies on age and gender as predisposing factors.