Objetive: Hypogonadism, a deficiency of the gonad to secrete testosterone and or spermatozoids is due to a primary testicular failure (hypergonadotrophic hypogonadism) or secondary to hypothalamic-pituitary disease (hypogonadotrophic hypogonadism). The physical changes of congenital hypogonadotrophic hypogonadism and severe hypoandrogenism by hypothalamic-pituitary organic causes has prevented mild clinical forms of functional origin in the postpubertal period to be suspected. The functional causes do not have phenotype changes and their signs: sexual dysfunction, infertility and general hypoandrogenism symptoms are not always investigated. It is a condition by exclusion of all other causes. Method: The hypothalamic factor causing the change in the ovarian-hypothalamic-pituitary axis has been known for ages, the condition being called hypothalamic amenorrhoea, in which, all organic and functional causes ruled out, can respond to progesterone (hypothalamic dysfunction) or not respond to it (hypothalamic insufficiency). Only in the last few years has the existence of hypothalamic functional hypogonadotrophic hypogonadism been established in the male, secondary to a systemic, endocrine, or idiopathic (no demonstrable cause) disease. Results: The concept of robustness of the male hypothalamus, which resisted psychological or metabolic stress factors that affected the female, has shown to be false, by demonstrating its lability with strenuous exercise, diet, etc. In males with idiopathic hypothalamic functional hypogonadotrophic hypogonadism, on not being able to perform the progesterone test which helps to differentiate severity levels of the GnRH, we believe that the clomiphene test can differentiate between a milder hypothalamic dysfunction (increase in testosterone with clomiphene), from a severe hypothalamic insufficiency (no increase in testosterone with clomiphene). Conclusions: We agree with other authors that this hypothalamic functional disorder may be the male counterpart of hypothalamic amenorrhoea. Clomiphene could be useful in the diagnosis and perhaps in the treatment of the forms with hypothalamic dysfunction. © 2008 Sociedad Española de Andrología.