['The purpose of the study was to compare the effectiveness of GnRH antagonist with luteal phase estradiol administration to GnRH agonist cycles, long protocol.', '55 IVF-ICSI patients received oestradiol in the luteal phase of the cycle, before a cycle with GnRH antagonist. Fifty-five patients submitted to IVF-ICSI with the use of agonist were allocated, age matched, as a control group (historical control). The primary outcome was the number of retrieved oocytes.', 'Patients were similar in terms of clinical characteristics. No differences were found in the number of oocytes retrieved (study group, 8.1 +/- 4.7; control group, 7.4 +/- 4.5) or in oocyte quality.'] Is luteal phase oestradiol administration in ovarian stimulation cycles with GnRH antagonist comparable to the GnRH agonist ( long ) protocol?