The role of the nasal passage in the pathophysiology of obstructive sleep apnea (OSA) is still controversial. To this end, induction of acute nasal obstruction in healthy volunteers is associated with sleep fragmentation and an increase in the number of obstructive and central apneas. Moreover, nasal topical anesthesia, which alters nasal reflexes, is associated with an increase in the number of obstructive and central apneas during sleep. Although nasal resistance is increased in patients with OSA, chronic nasal obstruction appears to play no significant role in the genesis, maintenance, or severity of OSA. Moreover, surgical correction of nasal obstruction does not alleviate OSA appreciably. The purpose of this review is to outline the current body of knowledge on the pathophysiology, diagnosis, and treatment of nasal obstruction in patients with OSA.