Sleep apnea, particularly obstructive sleep apnea, is a common disorder characterized by repetitive partial or complete cessation of airflow, associated with oxyhemoglobin desaturation and increased effort to breathe. In the 19th century, Broadbent defined this disorder as "perfect silence through two, three, or four respiratory periods in which there are ineffectual chest movements, finally, air enters with a loud snort, after which there are several compensatory deep inspirations." Middle-aged obese men are at particular risk, but the disorder is also present in women and young children. Since individuals with narrow airways or craniofacial anomalies may have an increased risk for obstructive sleep apnea or hypopnea syndrome, dentistry can play a pivotal role in identifying and possibly treating patients with this syndrome. This article reviews the role of an orthodontist in treating patients with sleep apnea syndrome (OSAS).