Abstract: Tonsillectomy (±adenoidectomy) is performed for recurrent tonsillitis or obstruction of the upper airway. Post tonsillectomy pain cumulates within first postoperative days and decreases gradually following the fourth day in pediatric patients with many adverse effects on the patients with 1% readmission was reported due to dysphagia and dehydration. The present study has been planned to assess the analgesic effect of tonsillar bed infiltration of levobupivacaine compared to levobupivacaine and magnesium after tonsillectomy in pediatric patients. Eighty American Society of Anesthesiologists (ASA) I children aged 7-13 years scheduled for elective tonsillectomy (±adenoidectomy) were included in current study. The patients’ Visual Analogue Scale (VAS) for pain were registered at 15th min after arrival to Postanesthesia Care Unit (PACU) and 1st, 2nd, 3rd, 6th, 12th and 24th h postoperatively. The time at the first analgesia request and additional analgesic requirements were also reported and patients were followed up for one week. Postoperative bleeding, infection, Post-Operative Nausea and Vomiting (PONV), abdominal pain, constipation, arrhythmia and allergic reactions were documented. Levobupivacaine plus magnesium gave significantly less VAS of pain in comparison to levobupivacaine alone at 12 and 24 h postoperatively. While this lower VAS of pain was found statistically non-significant at earlier periods of assessment. In addition, the time to first analgesic request was lengthened and total number of analgesic requests in the first 24 h were decreased in combined group when compared to levobupivacaine alone. In addition, laryngospasm significantly decreased in levobupivacaine plus magnesium group with no reported increase in complications. Adding magnesium to Levobupivacaine local infiltration in tonsillar bed is safe and significantly augments the analgesic effect of levobupivacaine after tonsillectomy in pediatric patients.