To define better the clinical presentation and perioperative outcome in children undergoing adenotonsillectomy (T&A) for relief of upper airway obstruction (UAO), we reviewed the hospital records of 60 consecutive, otherwise normal children aged 12 years or younger. Seven patients with trisomy 21, neurologic impairments, or preoperative cor-pulmonale were excluded. Intraoperative and postoperative complications were experienced by 15 (34%) and 13 (25%), respectively, of the 53 children with preoperative UAO. The most severe complications comprised pulmonary edema and prolonged postoperative oxyhemoglobin desaturation. Multivariate logistic regression analysis found a history of prematurity and/or low birth weight to be the most significant risk factors related to the occurrence of complications. Twenty-eight % of the study population had a history of prematurity and they had approximately 85% of the perioperative complications seen in children with UAO undergoing T&A. Other significant risk factors included adenoidal facies and evidence of respiratory distress at the time of surgery. It appears that T&A poses significant risk for children with UAO who were born prematurely and have evidence of abnormal facial development or respiratory distress preoperatively.