Postoperative complications following a large series of adenotonsillectomies (784 patients) at the Children's Hospital of Philadelphia fell into two major categories: hemorrhage and airway problems. Bleeding requiring operative intervention occurred in one child in the immediate postoperative period and in 16 children (2.0%) within 7-10 days. Eight patients (1.0%) had minor bleeding requiring only observation, and 9 others (1.2%) reported mild bleeding at home. Airway obstruction requiring the reinsertion of an airway or intensive care observation occurred in 10 children (1.3%). In general, these children were younger and most had significant underlying medical problems. We conclude that many complications encountered after adenotonsillar surgery are intrinsic to the patient's disease and overall medical condition. Improved surgical and anesthetic techniques have minimized the complications noted in earlier studies.