Lingual thyroid has been reported to cause obstructive sleep apnea (OSA) only once in the literature. We present a case of a 49-year-old nonobese female with a 2-year history of progressive snoring, apneas, snort arousals, and daytime somnolence associated with the sensation of an 'enlarging tongue'. She was found to have severe OSA caused by a large lingual thyroid. While positive airway pressure therapy was not successful, surgical resection of the thyroid was curative. OSA caused by lingual thyroid and other oropharyngeal/parapharyngeal tumors are discussed. A careful oropharyngeal examination is important in evaluating patients with complaints of OSA.