In order to diminish the cancellation rate due to a premature endogeneous LH surge and/or to a poor ovarian response and thus increasing the pregnancy rate, a GnRH agonist (Buserelin) was applied in patients starting their first ovarian stimulation with gonadotropins for IVF. All patients suffered from tubal infertility and were not older than 40 years. Each woman was allocated randomly to one of three groups: the conventional treatment with hMG alone (group I), patients from group II started the hMG treatment shortly after the LH rise caused by the GnRH agonist and patients in group III commenced the hMG treatment when an hypogonadotropic state was achieved after a long treatment of Buserelin. All male partners had a normal spermiogram. A reduction of poor responders to the superovulation is seen in the short-term group (6%), compared with the other two groups (14%). In some cases from group III ovarian cyst formation led to the cancellation of the treatment. The long-term group differs significantly from the other two in the duration of the gonadotropin stimulation and the number of ampoules hMG used. A severe ovarian overstimulation syndrome was not observed. There is no difference in the number of retrieved oocytes and the fertilization rate among the three groups. The pregnancy rate per cycle or per patient in the group with a short-term GnRH-agonist regimen is significantly higher compared to that of the group using the conventional hMG treatment.