Severe ovarian hyperstimulation syndrome (OHSS) was recorded in 8 of 413 patients after the use of gonadotropin-releasing hormone agonists (GnRH-a) associated with gonadotropins for in vitro fertilization. Seven of the 8 patients were pregnant. Common factors associated with the development of OHSS were high serum estradiol values on the day of ovulation induction and many follicles greater than or equal to 12 mm. Based on this experience, a new therapeutic schedule was used in a group of 10 patients who, after GnRH-a and gonadotropin stimulation, were judged to be at high risk of OHSS on the day of human chorionic gonadotropin (hCG). No hCG was administered and gonadotropins were stopped. The administration of GnRH-a was continued and, after a further period of pituitary desensitization, follicular stimulation was recommended with a lower dose of gonadotropins. No cases of OHSS occurred and 3 patients became pregnant.