To elucidate the mechanism of hypogonadotropic hypogonadism in a patient with X-linked congenital adrenal hypoplasia, we studied the effects on serum LH and FSH of repeated iv administration of GnRH (400 micrograms, over 2 h, once a day, for 14 consecutive days), pulsatile sc administration of GnRH (5 micrograms every 90 min during days 1 approximately 56, 10 micrograms every 90 min during days 57 approximately 91) and an iv bolus injection of 10 mg of naloxone. The repeated administration of GnRH restored the hyporesponsiveness of serum FSH and increased serum testosterone level from less than 1.0 to 1.7 nmol/l, but the impaired LH response to the standard GnRH test was not improved. The pulsatile administration of GnRH for 91 consecutive days did not induce a clinical or a biochemical change of puberty. Serum testosterone remained undetectable less than 1.0 nmol/l, the hyporesponsiveness of serum LH was not improved, but basal FSH level was significantly increased and the impaired FSH response to the standard GnRH test was slightly improved. Naloxone had no effect on serum LH or FSH before or during the pulsatile administration. We conclude that hypogonadotropic hypogonadism in our patient is due to the pituitary dysfunction and that the endogenous opioid peptides may not play a role in the mechanism of inhibited gonadotropin secretions.