The development of GnRH analogues enabling a hypophyseal desensitization with suppression of the gonadotrophic activity has opened new therapeutic possibilities in early puberty of central origin, metastatic prostate and breast cancers, endometriosis, fibromyomas and the syndrome of polycystic ovaries. This retrospective study concerning 93 cycles of in vitro fertilization between March and June 1987, compares the results of the combination of a GnRH agonist (busereline 0.3 mg s.c. x 2 days) with HMGs according to a "long protocol" or a "short protocol". For a mean stimulation time by HMG equivalent (13 days), the number of HMG vials is higher in case of a long protocol (40 vs 30). The mean estradiol level, on the morning of the induction is identical (2,096 pg/ml), as well as the mean number of ovocytes collected (6/tap). The segmentation rate appears to be better in case of long protocol (70% vs 45% in female indications), but there is no significant difference between the pregnancy rates (20 to 30%). The short protocol, less costly and simpler, seems therefore interesting in FIV, with patients without SOPK.