Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder. An association with sleep breathing disorder has not previously been established in the literature. We report the case of a 45-year-old woman with HD, presenting with snoring and observed apnea. Polysomnography showed obstructive sleep apnea with an apnea-hypopnea index (AHI) of 6.6 per hour including events up to 57 s long during rapid eye movement (REM) sleep. A trial of continuous positive airway pressure (CPAP) resulted in significant improvement in sleep structure, nocturnal respiration, daytime alertness, and subjective memory. Snoring, apneas, and respiratory arousals were abolished on CPAP. HD patients may suffer from sleep breathing disorder, and in spite of potential chorea, CPAP is feasible and may significantly improve their quality of life.