A new test is proposed for the sounding of the hypothalamic-pituitary functionality by means of the electric stimulation of the olfactory mucosa. Following the application, an appropriate electric stimulus in correspondence to the olfactory mucosa or of that which covers the middle turbinate, we noticed significant variations in the plasmatic cortísol (11-OHCS), which form a curve whose vertex corresponds to the 20th min following the application of the stimulus. The increase of the plasmatic 11-OHCS in normal subjects is always 100% greater than the basic values which are again reached at the 60th min. When the electrode is applied far from the olfactory mucosa (inferior turbinate), no change in the 11-OHCS values is obtained. In patients with post-operative anosmia, no change is obtained in the plasmatic values of the 11-OHCS. This excludes the possibility that the cortisolic response is merely dependent on a stress mechanism; consequently, a direct stimulation of the rhinencephalic structures, which are responsible for the neuro-secretion of the CRF-ACTH system, must be assumed. The stress prevents the cortisolic value from rising further following the olfactory stimulation; therefore the phenomena observed may depend on a state of refraction of the responsive structures (diencephalon, olfactory nerve) induced by the elevated steroid levels.