Obstructive sleep apnea is characterized by episodic sleep state–dependent collapse of the upper airway, resulting in periodic reductions or cessations in ventilation, with consequent hypoxia, hypercapnia, or arousals from sleep. Many patients are unaware that their breathing is affected and may not visit a physician for evaluation. The disease is commonand is an independent risk factor for motor vehicle accidents and cardiovascular disease. Home sleep apnea testing may be used to support, but not to rule out, the diagnosis of obstructive sleep apnea. Polysomnography is recommended in patients with a known or suspected history of stroke, a neuromuscular or pulmonary disorder with hypoventilation, or congestive heart failure or who are using opiates. Continuous positive airway pressure (CPAP) is considered first line therapy for symptomatic or moderate-to-severe obstructive sleep apnea. The use of alternative therapies (mandibular-advancement devices and various surgical options) for patients who decline or are unable to use CPAP should be considered on a personalized basis, with respect to the nature of obstruction, patient specific factors, and patient preferences. Recommended lifestyle modifications include weight loss counseling in overweight and obese patients, avoiding medications and substances that promote relaxation of the upper airway (e.g., alcohol, benzodiazepines, and narcotics), and increasing awareness of and providing counter measures for the risk of drowsy driving.