Background:Tonsillectomy is a common and painful procedure in children, often performed on an outpatient basis. Tonsillectomy is often associated with intraoperative bleeding and postoperative severe pain. Different methods such as drugs (nonsteroidal antiinflammatory drugs , opioids, corticosteroids ), adjustment of surgical technique and peroperative local anaesthetic infiltration have been used to reduce pain. It is known that pain after adenotonsillectomy or analgesic usage may lead to unwanted effects. For example, nonsteroidal antiinflammatory drugs may interfere with bleeding and opioids may cause respiratory depression, sedation or nausea and vomiting. There are some reported complications seen infiltrations of local anaesthetics into tonsillar and adenoid beds. No studies have assessed the effects of peritonsillar dexmedetomidine infiltration. Dexmedetomidine is a centrally acting sympatholytic agent that has intrinsic effect of regional anesthesia with amid anesthetic.Because of its analgesic and sedating activity, dexmedetomidine has been used previously as an nasal premedication in patients undergoing tonsillectomy, but its use, as a peritonsillar infiltration has not been evaluated. Dexmedetomidine is a highly selective alfa-2 adrenoreceptor agonist recently introduced to anesthesia practice producing dose-depended sedation, anxiolysis, and analgesia (involving spinal and supraspinal sites), without respiratory depression. Also Alpha-2 adrenergic agonists have peripheral analgesic effects. Therefore, this study was designed to compare the effects of preincisional, dexmedetomidine 2µg/kg peritonsillar infiltration by peritonsillar normal saline grup on intraoperative bleeding and hemodynamics, postoperative recovery including pain, sedation, nausea and vomiting in pediatric patients undergoing adenotonsillectomy, and the recording of any adverse effects that might develop during the 24-h study period.