BACKGROUND The identification of risk factors for the development of perioperative complications is one of the most important problems of pediatric anesthesiology. OBJECTIVE To identify risk factors for the development of perioperative complications in children undergoing ambulatory surgical interventions on ENT organs. METHODS Total of 141 patients were examined at the age from 7 to 17 years. Depending on the presence of complications all patients were divided into three groups: «No complications» (n = 64), «One complication» (n = 55) and «Two or more complications» (n = 22). The study was carried out in the following areas: Preoperative clinical status, intraoperative and postoperative complications. The severity of nasal breathing disorders was determined rhinomanometrically. 31 children underwent somnography. In the study of heart rate variability was evaluated. Intraoperative complications included: Cardiac arrhythmias, arterial hypertension and desaturation less than 90%. Postoperative complications included: Cardiorespiratory complications, pain, delirium, postoperative nausea and vomiting. RESULTS The most significant complication in the intraoperative period is desaturation below 90%, in the postoperative period they are pain, nausea and vomiting. Risk factors for the development of complications in the perioperative period are a decrease in the thyromental distance, hyperplasia of the tonsils of the third degree, Malampati score ≥ to 2 points, parents' bad habits, combined neurological and respiratory pathologies in a child, an assessment of the class «allergology» of the ASPOND scale is not less than 180 points and the prevalence of vagal influences. CONCLUSIONS The obtained results indicate that the presence of risk factors for perioperative complications during operations on ENT organs in children are associated with the initial autonomic status and the predominance of the parasympathetic nervous system as well as with clinical markers.