Sleep Apnea Syndrome is characterized by hypersomnolence, snoring, and sleep apnea. The symptoms of hypothyroidism include apathy, somnolence, lethargy, personality change, and intellectual deterioration and may be related to hypothyroid-related sleep disorders. Central, obstructive, and mixed patterns of sleep apnea may be observed in hypothyroidism. A 60-yr-old man was admitted due to hypersomnolence, snoring and generalized edema. Polysomnogram showed obstructive pattern of sleep apnea syndrome. Neck CT scan revealed narrowing of upper airway which is consistent with obstructive sleep apnea syndrome. Physical examination and hormonal study also disclosed the evidence of hypothyroidism. We report a case of sleep apnea syndrome due to primary hypothyroidism with review of literatures.