Upper airway imaging techniques have significantly advanced the understanding of the pathogenesis of obstructive sleep apnea and the biomechanical mechanisms by which therapeutic interventions for this disorder exert their effects. Both static and dynamic imaging studies have been used to examine the structure and function of the upper airway during wakefulness and sleep. These studies have highlighted the importance of the lateral pharyngeal walls in addition to the tongue and soft palate in modulating changes in upper airway caliber. Upper airway imaging has also been used to understand the changes in upper airway anatomy associated with weight loss, mandibular repositioning devices, and upper airway surgery. At present, upper airway imaging should be considered in patients undergoing upper airway surgery and possibly in patients being evaluated for oral appliances. MR imaging and nasopharyngoscopy are the imaging modalities of choice in patients undergoing a UPPP. Cephalometrics should be considered in patients being treated with mandibular repositioning devices. Upper airway imaging has provided an important framework to examine the pathogenesis of airway closure, and these investigations may, in time, lead to more effective treatment options for patients with sleep apnea.