The prevalence of obstructive sleep apnoea (OSA) in arterial hypertension ranges between 35 to 80 %, higher prevalence being in patients with resistant hypertension and metabolic syndrome. It is associated with an increased cardiovascular risk. Unfortunately it is often undiagnosed. OSA is a disorder characterized by recurrent upper airway collapse that occurs during sleep. The repeated airways obstructions lead to arousing from sleep, activation of sympathetic nerve system, blood pressure elevation and alteration of several metabolic parameters. The gold standard for treatment of moderate/severe OSA is positive airway pressure, which works by holding the airways open using a pneumatic splint and which leads to reduction of cardiovascular morbidity and mortality. For mild OSA the treatment lies in life style modification, mainly in body weight reduction.