Abstract: Objective：To explore the prophylactic efficiency of dexmedetomidine on postoperative nausea and vomiting (PONV) in highly susceptible patients. Methods：By using randomized and doubleblind controlled trial, 100 nonsmoking female patients receiving laparoscopic surgery were selected and randomly divided into dexmedetomidine group and control group. The dexmedetomidine group received 0.6 μg/kg dexmedetomidine before induction, and 3 μg/kg dexmedetomidine after surgery. The severity of PONV, the visual analogue scale (VAS）for pain scores, the use of rescued antiemetic and analgesic drugs were assessed for 48 h postoperatively. Results：There were 93 patients completed the study (47 cases in dexmedetomidine group and 46 cases in control group). The number of patients classified as PONV 0 in dexmedetomidine group was significantly more than that in the control group during the time interval 0 to 6 h postoperatively (37 vs 27, P＜0.05). The percentage of the usage of antiemetic drugs within 48 hours in dexmedetomidine group was lower than that in control group（25.5% vs 47.8%，P＜0.05）. During the time intervals 6 to 24 h and 24 to 48 h, the pain scores were significantly lower in dexmedetomidine group compared with control group, 2.9±0.9 vs3.4±0.7 and 2.7±0.6 vs3.0±0.7, respectively （P＜0.05）. Conclusions：Dexmedetomidine used perioperatively might decrease the severity of PONV in early phase postoperatively in highly susceptible patients, and reduce the need for antiemetic drugs and improve the analgesia effects.