BACKGROUND: Lipomas are common benign tumors, but they rarely occur in the retropharyngeal space and even more rarely occur in children. CASE REPORT: We report the case of an 11-year-old girl with a 5-year history of progressively worsening nasal obstruction, snoring, and excessive daytime sleepiness. Physical examination revealed a child with a body mass index of 16.9 kg/m2; otolaryngologic examination and imaging studies showed a large retropharyngeal mass. Polysomnography indicated an apnea-hypopnea index of 13.9 events per hour of sleep and a minimum oxygen saturation of 84%, with 20 episodes of desaturation to less than 90%. After complete excision of the mass, the patient's snoring, apnea, and daytime sleepiness resolved. CONCLUSIONS: Although lipomas in the retropharyngeal space are rare, clinicians should be alert to the possibility of this condition occurring in children who have symptoms of obstructed breathing during sleep but a normal body mass index and no other risk factors for obstructive sleep apnea.