Six women with polycystic ovarian syndrome were treated with a gonadotropin-releasing hormone agonist prior to ovulation induction with gonadotropins. Buserelin nasal spray (600 μg/day) was given for 6 weeks. There was a gradual and significant decrease in the level of luteinizing hormone (LH) during the treatment period. No change was observed in the level of follicle-stimulating hormone. The estradiol, estrone, testosterone and androstenedione levels decreased significantly. No reduction was seen in the DHEAS level. After 4 weeks of treatment LH had reached postmenopausal levels, and testosterone and androstenedione were within the normal range. It is concluded that 4 weeks’ treatment with 600 μg buserelin intranasally per day is sufficient to normalize the ovarian androgen production in polycystic ovarian syndrome prior to gonadotropin stimulation and to reduce the LH level avoiding premature luteinization or spontaneous LH surge.