Background: There is some evidence that intraoperative magnesium infusions prevent postoperative delirium in children.Objective: The aim of the work was to study the effects of intra-operative magnesium sulphate administration on the children's risk of post-adenotonsillectomy post-agitation.Patients and Methods: At Anesthesia & Surgical Intensive Care Department, Zagazig University Hospitals, this randomized, double-blind clinical trial included 90 children with American Society of Anesthesiologists (ASA) physical status classes I or II who were scheduled to undergo adenotonsillectomy. Patients were allocated randomly into two equal groups (45 for each group): Group C: received intraoperative 0.9% normal saline initial loading dose of 0.3ml/kg over 10 min as a bolus, then 0.1ml/kg/hr. of infusion for the length of the procedure. Group MG: Patients were given 30 mg/kg of a 10% solution of magnesium sulphate intraoperatively over the course of 10 minutes as an initial loading dose, then 0.1ml/kg/hr. of infusion for the length of the procedure.Results: Group MG was significantly lower than Group C regarding fentanyl needed and also total dose of fentanyl. As regard Pediatric Anesthesia Emergence Delirium (PAED) score, we found that there was No significant difference regarding pre but at post group MG was significantly lower at post also agitation was significantly associated with Group C.Conclusion: It could be concluded that sevoflurane anesthesia using magnesium sulphate is used for adenotonsillectomy surgery in children. A 30-mg/kg loading dose is given intraoperatively, followed by a continuous infusion at 0.1ml/kg/hr. for the duration of surgery. This combination reduces the incidence of emergent anxiety and the need for postoperative fentanyl