Radioimmunoassays were used repeatedly to determine prolactin, LH, FSH, estradiol and progesterone at different time intervals (days, months, weeks) in 50 women with hyperprolactinemic amenorrhea. Nine patients had x-ray signs of hypophysial adenoma. The intact state of the portal system, hypophysis gonadotrophs and thyrotrophs was confirmed using LH-RH and TRH tests. Proceeding from the comparison of gonadotrophin and sex steroids and the analysis of the blood LH fluctuation amplitude after repeated measurements, it was concluded that the gonadotropic basal secretion was disturbed in hyperprolactinemic amenorrhea and that a single determination of an elevated gonadotrophin level in the blood was not enough to diagnose primary ovarian insufficiency.