BACKGROUND:: Postoperative nausea and vomiting (PONV) is a frequent complication in postoperative period. The aim of this article was to evaluate the effect of dexmedetomidine on PONV. METHOD:: RevMan 5.3 software was applied for performing statistic analysis. Twenty-four trials with 2046 patients were included. RESULTS:: The PONV of the dexmedetomidine group was significantly lower compared with the placebo group (0.56, 95% CI: 0.46, 0.69). Subgroup analysis further confirmed the effect of dexmedetomidine (irrespective of administration mode) (P < 0.00001). Perioperative fentanyl consumption in dexmedetomidine group were also reduced significantly (P < 0.00001). Whereas, side effects such as bradycardia, hypotension increased in dexmedetomidine group (especially in loading dose mode and loading dose plus continuous infusion mode). CONCLUSIONS:: Dexmedetomidine administrated in continuous infusion mode has the advantage to prevent PONV as well as reduce side effects such as bradycardia and hypotension.