90 children (ASAⅠorⅡ,aged 2-5 yr) undergoing unilateral orchiopexy or inguinal herniorrhaphy were included in this study. Anesthesia was induced with sevoflurane via a facemask, followed by placement of a laryngeal mask airway. Anesthesia was maintained with sevoflurane 2-3% in oxygen-air.Then,caudal block was applied. Patients were randomly assigned in three groups. Group Cau-DEX (n = 30): Caudal Levobupivacaine 0.25% 1ml/kg plus dexmedetomidine 1µg/kg and 10 ml normal saline i.v.;Group IV-DEX(n = 30): Levobupivacaine 0.25% 1ml/kg and dexmedetomidine 1µg/kg(10 ml)i.v.;Group Placebo(n = 30): Levobupivacaine 0.25% and 10 ml normal saline intravenous.