Endogenous opioids exert a tonic inhibitory control on GnRH pulsatility at the hypothalamic level and it must be responsible for some hypogonadotropic hypogonadic syndromes such as functional hypothalamic amenorrhea (FHA). We treated 22 patients suffering from FHA with an oral anti-opioid drug, Naltrexone Hydrochloridrate (NH), 50 mg once a day or placebo, in a double blind controlled study. Six patients exhibited a regular resumption of their menstrual cycles (4 on placebo and only 2 on NH). There was an increase of 17BE2 in 3 of these 6 patients; progesterone levels did not change at all. Gynaecological echography demonstrated folliculogenesis in 4 of these 6 patients (only 1 on NH). The results show that NH is not a real therapy in patients suffering from FHA. Furthermore placebo, useful to the resumption of menstrual bleeding in 4 patients, underlines the importance of psychosomatic effects in the therapeutic management of FHA.