Background Emergence agitation is a common problem in pediatric anesthesia,especially after sevoflurane induction and maintenance anesthesia.The purpose of this study was to investigate the effect of sufentanil to reduce emergence agitation after sevoflurane anesthesia in children undergoing adenotonsillectomy compared with fentanyl.Methods One hundred and five children,aged 3-11 years,were randomly allocated to receive normal saline (control group),sufentanil 0.2 μg/kg (S2) or fentanyl 2 μg/kg (F2) 1 minute after loss of the eyelash reflex.Anesthesia was induced and maintained with sevoflurane.Time to tracheal extubation,recovery time,Paediatric Anesthesia Emergence Delirium (PAED) scale,and emergence behavior were assessed.Results The incidence of severe agitation was significantly lower in S2 and F2 groups vs.the control group,4/32 and 15/34 vs.24/34 respectively,(P＝0.002,0.009,respectively).PAED scales were significantly different among three groups (P＝0.007),and lower in the S2 and F2 groups than in the control group (P＝0.007 and P＝0.025,respectively).And the incidence of severe agitation and the PAED scale score was significantly different between the S2 and F2 groups (P＝0.007,P＝0.019,respectively).Time to tracheal extubation and recovery time were similar in all three groups.Conclusions Administration of sufentanil at 0.2 μg/kg after induction of anesthesia reduced emergence agitation in children receiving sevoflurane anesthesia for adenotonsillectomy compared with fentanyl.This was without delaying the recovery time or causing significant hypotension.