After irradiation of the neck for a squamous cell carcinoma of the tonsillar pillar and vocal cord, a 71-year-old man presented with a rapidly progressive sleep apnea syndrome. Previous reports describe the condition of patients with obstructive sleep apnea that developed after neck irradiation and secondary to supraglottic edema. Our patient had an obstructive component to his apnea similar to that described in previous cases, but, in addition, he had hypothyroidism. Myxedema is a well-described cause of both obstructive and central apnea. We believe both contributed to his condition. He was successfully treated by placement of a tracheostomy and by thyroid supplementation. In patients who present with sleep apnea after neck irradiation, especially with acute or severe symptoms, the differential diagnosis should include both a central cause from hypothyroidism as well as a peripheral obstructive cause from laryngeal edema.