Objective: To evaluate the safety and efficacy of temperature-controlled radiofrequency tonsil reduction in the treatment of children with a sleep-related breathing disorder associated with tonsillar obstructive hypertrophy. Design: Prospective, nonrandomized, case series feasibility study of children meeting the criteria for tonsillectomy or adenotonsillectomy for the treatment of an obstructive sleep-related breathing disorder. Setting: Community-based hospital. Patients: Ten children, aged 4 to 13 years, presenting consecutively to a community-based otolaryngology practice with tonsillar or adenotonsillar obstructive hypertrophy implicated clinically in causing a sleep-related breathing disorder; their parents consenting to temperature-controlled radiofrequency tonsil reduction instead of surgical tonsillectomy. Intervention: Temperature-controlled radiofrequency tonsil reduction, along with surgical adenoidectomy, if adenoids were present, under general anesthesia. Main Outcome Measures: Tonsil size reduction, treatment morbidity, and symptom improvement with follow-up to 1 year. Baseline and 3-month posttreatment polysomnographic data were used. Results: There was a reduction in tonsil size at 1 year of 75.0% on average, without evidence of regrowth during the 1-year follow-up. All children were drinking liquids in the recovery room, and most were eating soft diets within 6 hours; 8 of the 10 children were eating a normal diet by day 5. On average, the return to normal activity was 3.9 days, with 2.9 days of parental loss of work time. Quality-of-life variables all improved. Snore indexes decreased by 88.6%. Polysomnography at 3 months revealed an 84.2% reduction in the apnea index and a 52.3% reduction in the apnea/hypopnea index. There were no complications. Conclusion: Temperature-controlled radiofrequency tonsil reduction seems to be a safe, effective, and minimally morbid treatment for tonsil hypertrophy in children with obstructive sleep-related breathing disorders.