All women receive 21 days of an oral contraceptive. A MF protocol will be used for ovarian stimulation in 90 patients. Three days after the last pill, a GnRH-agonist buserelin (Suprefact, Aventis Pharma, Frankfurt, Germany) 50 µg SC twice daily will be initiated and two days after that, recombinant FSH (Gonal-F, Serono, Aubonne, Switzerland) or hMG (Merional, IBSA, Lugano, Switzerland) 300-450 IU/day will be administered. Ninetyty patients will be assigned to an A/L protocol. After oral contraceptive withdrawal bleeding on day 3 of cycle, recombinant FSH or hMG 300-450 IU/day will be initiated and letrozole (Femara, Novartis, East Hanover, NJ) 5 mg/day will be administered for 5 days. When the dominant follicle reached 14 mm in mean diameter, ganirelix acetate (Antagon, Organon, West Orange, NJ) 0.25 mg SC daily will be started.