Objective To evaluate the effectiveness of GnRH antagonist in vitro fertilization-embryo transfer (IVF-ET) in polycystic ovary syndrome (PCOS) patients.Methods Such databases as PubMed (1997 to 2010), PML (1997 to 2010), FMJS (2000 to 2010), CBMdisc (1979 to 2010), CNKI (1994 to 2010), VIP (1989 to 2010), WanFang (1994 to 2010), and duxiu scholar searcher (www.duxiu.com), and nine relevant Chinese journals were searched for retrieving the randomized controlled trails (RCTs) on the effectiveness of GnRH antagonist versus GnRH agonist for IVF-ET in PCOS Patients. The studies were screened according to the inclusive and exclusive criteria by two reviewers independently, the data was abstracted and the quality was evaluated. The RevMan 4.2.7 software was used for Meta-analyses. Results Six grade-B studies involving 699 participants were included. The results of Meta-analyses showed that, compared with the GnRH agonist, there was no significant difference in the GnRH antagonist group about the stimulation duration (WMD= –1.23, 95%CI –2.76 to –0.31), dose of gonadotrophins (Gns) (WMD= –4.87, 95%CI –14.20 to 4.46), serum E2 value on the day of HCG administration (WMD= 31.37, 95%CI –263.40 to 326), number of oocytes retrieved (WMD= 1.34, 95%CI –1.02 to 4.70), clinical pregnancy rate (OR= 1.27, 95%CI 0.77 to2.10), and miscarraige rate (Peto OR= 0.67, 95%CI 0.38 to1.18). But the OHSS rate in the GnRH antagonist group was lower with a significant difference (Peto OR= 0.35, 95%CI 0.24 to 0.50). Conclusions Compared with the GnRH agonist protocol, the GnRH antagonist protocol can obviously reduce the incidence of OHSS, but has the same effect in Gn dose, retrieving oocytes and clinical pregnancy rate. Because the GnRH antagonist can decrease the treatment duration and cost, and has better safety, so it may be an ideal choice for PCOS patients to have IVF-ET therapy. For the quality and quantity limitation, and the methodology difference of the included studies, it is suggested that the conclusion from this study should be only served as a reference of clinical analyses, and should be revaluated and updated unceasingly.