Gonadotropin Releasing Hormone(GnRH) appears to represent a more physiologic approach to increasing the release of the pituitary gonadotropin endogenously. This therapeutic agent is still being investigated. Among various modes of administration, nasal spraying can be taken because of its convenience. To elucidate whether intermittent nasal spraying of GnRH induce down regulation in idiopathic male infertility or not, we have used nasal spraying of natural GnRH 200 microgram and GnRH analogue 100 microgram every 8 hours in 9 patient and in 5 ones respectively. All patients revealed normal findings of external genitalia and hormone profile(Lutenizing Hormone, Follicular Stimulating Hormone, Testosteron and Prolactin). Among 5 patient who were treated with GnRH analogue 100 microgram every 8 hrs, there were two case of decreased gonadotropin and testosteron, suggesting down regulation. However all patients treated natural GnRH 200 microgram every 8 hours showed a normal and/or slightly elevated gonadotropin level, so this protocol could be regarded as a acceptable dosage not to inducing down regulation. This results show that natural GnRH is superior to the anologue one in treating the idiopathic male infertility.