Objective?To evaluate the efficacy and safety of 5 HT-3 receptor inhibitor tropisetron injected in the postoperative nausea and vomiting (PONV) after general anesthesia. Methods?We searched the PubMed, EBSCO, Springer, Ovid, and CNKI to identify randomized controlled trials (RCTs) about tropisetron in preventing PONV after general anesthesia from January 1995 to September 2009. We also consulted references of the included studies for omission. The methodological quality of the included RCTs was assessed and data were extracted according to the standard of the Cochrane Handbook 5.0.1. The meta-analyses were performed by RevMan 4.2.10 software. Results?A total of 17 RCTs involving 4 678 patients were included. The results of meta-analyses showed that: (1) Efficacy: tropisetron injected could decrease the incidence of PONV after general anesthesia (RR=0.41, 95%CI 0.29 to 0.60), and decrease the incidence of PONV after general anesthesia with opioid drugs in patient controlled analgesia (RR=0.30, 95%CI 0.15 to 0.60); tropistron injected once or more could decrease the incidence of PONV in combination of PCA with tramadol (RR=0.41, 95%CI 0.29 to 0.56; RR=0.10, 95%CI 0.06 to 0.19); and tropisetron combined with dexamethasome could also lessen the incidence of PONV (RR=0.27, 95%CI 0.13 to 0.57). (2) Safety: Tropisetron injected could lessen the incidence of postoperative headache and dizziness (RR=0.35, 95%CI 0.16 to 0.75), but could not significantly decrease the pruritus and somnolence. Conclusion?Tropisetron injected can significantly decrease the incidence of PONV after general anesthesia, and it will not increase the adverse effect and the incidence of postoperative complications. Furthermore, it has also the advantage of decreasing postoperative headache and dizziness.