Obstructive sleep apnea syndrome (OSA) is a condition affecting up to 5% of the population, in which episodes of upper airway obstruction lead to temporary cessation of airflow, disturbed sleep architecture and daily somnolence. The health consequences of OSA also include psychological and cognitive deficits, an increased risk of systemic and pulmonary hypertension, coronary disease, bradyarrhythmias and motor vehicle accidents. Symptoms and complications of OSA lead to a significant decrease of health-related quality of life (HRQOL) of affected patients. We review the current literature on HRQOL effects of OSA and its treatment. There is good evidence of beneficial effect of the continuous positive airway pressure (CPAP) therapy on the quality of life of patients with OSA. Improvements in HRQOL are most appreciable in patients with moderate to severe OSA, although they also seem to be present in selected patients with mild OSA. The effects of dental devices and surgical procedures on HRQOL of patients with OSA have not been studied in randomized, placebo-controlled trials. Health-related quality of life has become one of the major outcome measures in patients with sleep apnea. Assessment of HRQOL has become a crucial part of any clinical study involving patients with OSA.