Objective To investigate the efficacy and safety of dexmedetomidine on prevention of emergence agitation in adult patients during recovery period after abdomen surgery. Methods 120 ASA I-II patients scheduled for elective abdominal surgery under general anesthesia were randomly divided into three groups: dexmedetomidine group (group A), midazolam group (group B) and the saline control group (group C), 40 cases in each group.40min before the end of surgery, dexmedetomidine 0.6μg/kg was continued intravenous infusion 10min in group A, midazolam 30μg/kg and 1mL physiological saline were respectively intravenously injected in group B and group C.The postoperative recovery room (PACU) of restlessness, sedation, blood pressure, SpO2 and extubation time were observed. Results In of midazolam group, the time of anesthesia recovery[(18.2±1.9)min], extubation[(32.1±3.9)min]and PACU staying[(48.7±3.1)min]were significantly longer compared with the dexmedetomidine group[(13.1±2.4)min, (26.5±2.2)min and (39.8±3.4)min, P=0.023, 0.040 and 0.003]and the saline group[(12.6±2.3)min, (24.8±2.9)min and (38.6±4.3)min, P=0.017, P=0.023 and P=0.001].The postoperative sedation scores of dexmedetomidine[(2.3±0.2)points, P=0.025]and midazolam group[(2.4±0.1)points, P=0.020] were significantly higher than the saline control group[(1.1±0.5)points].The postoperative agitation score of dexmedetomidine (1.3±0.5)points was lower than midazolam group [(2.5±0.5)points, P=0.011] and the saline control group[(2.4±0.6)points, P=0.020].HR and MAP of three groups at 2 min before extubation were observed, in the immediate extubation and at 5 min after extubation, the HR of dexmedetomidine group[(62.7±4.1)times/min, (67.3±3.4)times/min and (63.2±4.3)times/min]was significantly delayer than midazolam group [(72.3±3.4)times/min, (84.9±5.3)times/min and (82.1±3.1)times/min], (P=0.002, P=0.001 and P=0.001) and the saline control group [(73.6±2.9)times/min, (85.3±4.7)times/min and (83.3±4.5)times/min], (P=0.001, P=0.023 and P=0.038) at the three time.In the immediate extubation, the MAP of patients in dexmedetomidine group[(87.3±4.2)mmHg)]was lower than midazolam group[(93.1±4.3)mmHg, P=0.001]and the saline control group[(95.6±5.8)mmHg, P=0.001].At 5 min after extubation, the MAP of patients in both of dexmedetomidine[(84.5±3.1)mmHg)]and midazolam[(85.1±2.9)mmHg]group were lower than that in the saline control group[(92.3±4.6)mmHg, P=0.023 and P=0.038]. Conclusion Dexmedetomidine could be one of the ideal drug to relieve emergence agitation in adult patients during recovery period after abdomen surgery and the curative effect is better than midazolam. Key words: Dexmedetomidine; Anesthesia, general; Surgical operation