Fifty four women with repeated unsuccessful in vitro fertilization (IVF) cycles due to inadequate ovarian response to stimulation with human menopausal gonadotropins (hMG) participated in this study. They were randomized to receive either gonadotropin releasing hormone agonist (GNRHa), Buserelin, prior to and during induction of ovulation by hMG (Group I--long protocol), or GnRHa starting on the first day of the cycle together with induction of ovulation by hMG (Group II--short protocol). Mean follicular phase serum luteinizing hormone (LH) and progesterone (P) levels were significantly lower in Group I than in Group II (P less than 0.01). Cancellation rate was significantly lower in Group I than in Group II (P less than 0.01). The long GNRHa protocol resulted in statistically significant lower cancellation rates, more oocytes per pickup (OPU), more embryos transferred per patient, and a higher pregnancy rate. Significantly more hMG ampoules and more treatments days were required in the long GNRHa protocol. Our data demonstrate that the use of GNRHa prior to and during ovarian stimulation with hMG offers a very good alternative for patients with repetitive unsuccessful IVF cycles due to inadequate response.