 This was a prospective and randomized study undertaken between January 2004 and December 2007. One hundred patients with an indication for oocyte donation with functioning ovaries and IVF with or without intracytoplasmatic sperm injection ICSI were recruited for the study. After assignment to IVF or IVFICSI randomization was performed to 1 of the 2 treatment groups GnRH agonist or GnRH antagonist during endometrial preparation in oocyte donation recipients using a computed-generated randomization schedule assigned via numbered sealed envelopes. 