PURPOSE OF REVIEW: To define the relationship between obstructive sleep apnea (OSA) and nasal obstruction, we have reviewed the literature on epidemiological, physiological, and randomized controlled studies in which the relationship between nasal obstruction and OSA was investigated. RECENT FINDINGS: Data from observational studies suggest that nasal obstruction contributes to the pathogenesis of OSA. Recently, studies have mainly focused on the effects of therapeutic interventions on the nose and OSA. Eleven trials with randomized controlled designs were found; external nasal dilators were used in five studies, topically applied steroids in one, nasal decongestants in three, and surgical treatment in two studies. Data from these studies showed only minor improvement in the symptoms and severity of OSA. SUMMARY: The current evidence suggests that the nose may not play a significant role in the pathogenesis of OSA. The impact of treating nasal obstruction in patients with OSA on long-term outcome remains to be defined more accurately through randomized controlled trials of medical and surgical therapies with large numbers of patients.