This study compared three groups of patients treated with three different protocols of suppression of the pituitary-ovarian axis prior to and during gonadotropin stimulation for in vitro fertilization with a nonsuppressed control group. Patients treated with daily injections of DTRp6 (Decapeptyl 0.5 mg) or with a single injection of Decapeptyl depot (3.2 mg CR) had a longer folicular phase than patients treated with Buserelin (1.2-1.5 mg daily) and the patients in the control group. The number of human menopausal gonadotropin ampules required to reach adequate stimulation was also significantly higher in the former two groups of patients. The number of oocytes recovered (6-7 per patient), fertilized (45-58%) and cleaved (92-100%) did not differ among the groups. Peak estradiol levels and the pregnancy rate were highest in the group treated with Buserelin. The overall picture would indicate that suppression with Buserelin was the least profound.