Ten infertile menstruating women treated with daily injections of gonadotropin-releasing hormone agonist (GnRH-a). The GnRH-a (Buserelin; Hoe 766, Hoechst-AG, Frankfurt/Main, West Germany) was administered subcutaneously (SC) from day 9 of the cycle for 6 days, and intranasally (1.2 mg) for 15 days. Before treatment, all ten women had a normal response to Buserelin challenge test and the GnRH test, and seven of the ten responded to estradiol (E2) benzoate tests (2 mg intramuscularly). The SC administration of Buserelin (1.5 mg) for 6 days resulted in suppression of pituitary activity. Continuous treatment with Buserelin (1.2 mg for 3 weeks) was effective as demonstrated by decreasing serum E2 levels to below 20 pg/ml, and in the absence of ovarian follicles in ultrasonographic scanning. Three days after cessation of Buserelin treatment, the pituitary again responded to the GnRH test. Thus, the authors concluded that the administration of Buserelin in very high doses can induce medical hypophysectomy within 6 days, but over 3 weeks of suppression therapy are required to abolish ovarian findings. Desensitization of the pituitary was reversible within 3 days of cessation of the treatment.