This article reviews the terminology of obstructive sleep apnea and the associated diagnostic tests and provides an overview of the risk factors for this chronic condition. Sleep apnea affects 2% to 4% of middle-aged working adults in the general population, however, a considerable number of affected individuals remain undiagnosed. Patients with the disease may be at a higher risk for adverse perioperative outcomes. Knowledge of factors associated with an increased risk of obstructive sleep apnea is vital to the perioperative assessment and anesthetic plan.