Clomiphene citrate was administered to 17 patients with either secondary amenorrhea or oligomenorrhea to study its effect on hypothalamic-pituitary response. Measurement of pulsatile gonadotropin output was accomplished utilizing samples collected every 20 minutes for 6 to 8 hours before and after clomiphene administration. Response to 100 mug synthetic luteinizing hormone releasing hormone (LRH) was measured at the end of the sampling period. Patients with polycystic ovarian disease who ovulated showed increased baseline FSH and LH, decreased peak LH, and a decrease in the percentage increase over baseline for both LH and FSH. On patient wil clinical anorexia nervosa responded to clomiphene as an estrogen, with lowered baseline LH and FSH values. Patients with resolving anorexia responded to clomiphene as an antiestrogen, with increased baseline gonadotropins, and decreased gonadotropin peak values. A patient with a surgically treated chromophobe adenoma showed no change in parameters measured before and after clomiphene administration. Baseline and pulsatile LH output appear to reflect the tonic output of gonadotropin as affected by estrogen acting in a negative feedback system, and the peak response to LRH administration, the response to the positive feedback of estrogen. Thus, LRH stimulation in clomipheneresistent patients may be of value in diagnosing the site and degree of the defect and aid in improving therapy.