Obstructive sleep apnea syndrome (OSAS) is a respiratory disorder affecting up to 49 % and 23 % of middle to older aged men and women respectively. CPAP (continuous positive airway pressure) is the gold-standard treatment for severe apneas. In mild and moderate forms of OSAS, mandibular advancement devices (MAD) are equally a first line of treatment. Both CPAP and MAD have their advantages and side effects. Patient tolerance to these two therapies varies according to different patient-parameters. In order to guide physicians and patients in choosing between these two treatments, we present a description of both treatment modalities.