Women with PCOS are at risk to develop OHSS when stimulated with gonadotrophins for IVF. For this reason in this study the degarelix was tested in order to minimize the risk of OHSS as well as to improve the pregnancy rate in these patients. The use of long acting GnRH antagonist promotes a deep suppression of LH and consequently the activity of theca cells, which secrete androgens (the precursors of estradiol), and consequently the levels of estradiol remains low. Comparing the long acting GnRH antagonist at the first day of cycle with a flexible GnRH antagonist protocol in a group of patients with PCOS will be useful in order to establish the best way to perform controlled hyperstimulation in IVF cycles and minimize the risk of OHSS.