We report a case of Jakob-Creutzfeldt's disease (amaurotic form of Heidenmain's disease) showing typical clinical, anatomical, microscopic and electrophysiologic (E.E.G, polygraph sleep recordings, Evoked Potential) signs. Changes in visual Evoked Potentials were quite specific whereas Auditory and Somesthesic E.P'. were not modified. Early elements (O, I, II, and III having a latency of less than 100 ms) were strongly developed, while later elements of the associative type were absent. The precociousness and specificity of the E.P. abnormalities are stressed in the differential diagnosis of J.-C's disease from other insanities, or from cortical blindness of other aetiology. The physiopathologic implications of electrophysiological data is discussed to illustrate the possibility of using Evoked Potentials to help resolve the problems of functional cerebral stratigraphy in man.