OBJECTIVE.: Although adenotonsillectomy is the accepted treatment for obstructive sleep apnea (OSA) in the pediatric population, tonsillectomy has not been widely adopted in adults, and its success in this group has not been well reported. Despite the lack of current evidence, there may be an important role for tonsillectomy in selected adult cases, and further study is required. This is a pilot study from a larger group of subjects currently enrolled and awaiting surgery and repeat polysomnography. STUDY DESIGN.: Retrospective series with chart review. SETTING.: Tertiary referral teaching hospitals. SUBJECTS AND METHODS.: Thirteen consecutive eligible subjects with tonsillar hypertrophy and OSA were identified after treatment. These patients had undergone pre- and postoperative polysomnography for assessment of the severity of sleep-disordered breathing. Post hoc analysis of key parameters was performed by Wilcoxon signed rank and paired t tests. Tonsillectomy was performed on all subjects, using the diathermy dissection technique. Nasal surgery was performed simultaneously in 11 subjects for symptomatic nasal blockage unresponsive to medical treatment. RESULTS.: There was a statistically significant improvement in the severity of OSA after surgery. The total Respiratory Disturbance Index (RDI) was significantly decreased from median values of 31.7 to 5.5 (P = .0002). The RDI in rapid eye movement and non-rapid eye movement sleep and the arousal index were also significantly decreased. CONCLUSION.: In selected adult subjects, tonsillectomy with intercurrent nasal surgery should be considered an effective treatment for OSA and may reduce the requirement for continuous positive airway pressure, oral appliances, or further therapeutic intervention.