This article reviews the current insights in the contribution of nasal physiology, resistance and pathophysiology in relation to sleep-related breathing disorders. Different possible pathways have been followed to prove a clear role for the nose in this matter; they are reviewed and discussed. From all this it should be concluded that today there is only evidence for abnormal nasal resistance to be a possible cofactor in the disease. A short reminder about the currently available diagnostic tools for assessing nasal patency and resistance is given next. Finally the relation between the nose and treatment of sleep-related breathing disorders with nocturnal continuous positive airway pressure is discussed.