To evaluate the effect of luteal estrogen supplementation on pregnancy rates in normal responder IVF patients treated with recombinant FSH and fixed multidose GnRH antagonist, patients were randomized into two groups to receive vaginal 600 mg/d micronized progesterone for luteal phase supplementation with or without transdermal estrogen supplementation (100 microg/d). Because pregnancy rates and ongoing pregnancy rates were similar with and without estrogen supplementation (50.0% vs. 55.2% and 36.6% vs. 34.4%, respectively), we concluded that luteal estrogen supplementation in fixed multidose GnRH antagonist cycles did not change the pregnancy rates significantly.