Objective:To confirm the value of GnRH antagonist(GnRHant) cetrorelix in preventing the occurrence of premature LH surges and compare a multiple dose and a single dose GnRHant protocols for the COS of IVF/ICSI patients with a short GnRHa protocol. Methods:Single-center randomized,prospective,controlled study was conducted in our study.Ninety infertile women who underwent ovarian stimulation for IVF-ET were selected.Multiple dose of 0.25 mg(Group I) and single dose of 3 mg(GroupⅡ)of cetrorelix(60 patients) was administered in the late follicular phase.A depot preparation of triptorelin(Decapeptyl) was chosen as a control agent(30 patients)(GroupⅢ).Ovarian stimulation was conducted with FSH. Results:No premature LH surge occurred after cetrorelix administration.The mean numbers of mature oocytes obtained from patients were(13.47 7.60),(18.66 8.37) and(15.77 10.78) in GroupsⅠ,ⅡandⅢ,respectively, showing no statistical difference.The fertilization rates were(78.97 18.11)%in GroupⅠ,(72.35 25.44)%in GroupⅡand(76.80 23.10)%in GroupⅢ.The clinical pregnancy rates of patients were statistically comparable in the GnRHa group(30.8%) and in the GnRHant group(37.9%in GroupⅠ,28.6%in GroupⅡ),as ongoing pregnancy rates of embryo transfer were 31.0%,25.9%,30.8%for the GroupⅠ,ⅡandⅢ,respectively.The miscarriage rate was not different in the three groups.There were four patients cancelled embryo transfer for preventing severe ovarian hyperstimulation syndrome(OHSS) in triptorelin group,and 1 patient in each cetrorelix group.No severe or moderate OHSS of cetrorelix groups occurred. Conclusion:Both single-dose and multi-dose cetrorelix protocols prevented premature LH surges in all patients studied.GnRHant and GnRHa provide comparable results in patients,while GnRHant allows a higher flexibility in the treatment.