The aim of the present study is to compare the effect of IV infusion 0.5 µg/kg dexmedetomidine and IV 0.1 mg/kg nalbuphine in preschool children for prevention of emergence agitation after adenotonsillectomy under sevoflurane anesthesia.

Consent will be obtained from legal guardian of children,patients will be randomized according to computer randomization to one of two groups, dexmedetomidine group (DEX)group who will receive 0.5 µg/kg dexmedetomidine diluted in 50 ml of normal saline 0.9% to be given by IV infusion over 10 minutes after induction of anesthesia then 5ml of 0.9% normal saline IV ,nalbuphine group (NAL)group will receive IV infusion of 50 ml of 0,9%normal saline by IV infusion over 10 minutes then 0.1mg/kg nalbuphine diluted in 5ml of 0.9%normal saline IV after induction of anesthesia.

Inclusion Criteria:

• Children of (American Society of Anesthesiologist)ASA physical status grade I or II.
• Aged 2-5 years
• Undergoing elective adenotonsillectomy.

Exclusion Criteria:

• History of hypersensitivity to the studied drug.
• Refusal of the legal guardian to participate in the study.
• Severely agitated child at induction of anesthesia
• Occurrence of postoperative bleeding at(Post Anesthesia Care Unit) PACU