OBJECTIVE The undeniable asset of the antagonist protocols in in vitro fertilization is the decrease of the risks of ovarian hyperstimulation syndrome, by the use of a release by GnRH agonist. Nevertheless, questioning persist concerning the rates of clinical pregnancies, the oocyte quantity and the empty follicle syndrome. We thus studied these parameters in our center. METHODS A retrospective study was realized from January 1st, 2013 till July 31st, 2015. The main objective was the evaluation of the rate of clinical pregnancies in antagonist protocol. A first group of 775 cycles have benefited from a release of the ovulation by HCG, while a second group of 204 cycles, by GnRH agonist. The secondary objectives were the oocyte quantity, the rate of ovarian hyperstimulation syndrome, and the rate of empty follicle syndrome. RESULTS No statistically significant difference was found between both groups concerning the rates of clinical pregnancies, oocytes quantity, and the rate of empty follicle syndrome, whatever is the type of used release, in fresh embryo transfer. A syndrome of premature ovarian hyperstimulation syndrome was found at 7.9 % of the patients in the group 2 versus 2.3 % in the group 1, with a statistically significant difference (P<0.05). At these patients, a strategy of frozen embryo transfer ("freeze all") was proposed. The accumulated rates by pregnancy in both groups were not statistically different. CONCLUSIONS The release by GnRH agonist does not show inferiority in terms of clinical pregnancy, in comparison to HCG.