The effect of intensity tipon the amplitude of the cortical potential evoked by electrical stimulation of the contralateral VIIIth nerve in an anesthetized guinea pig was studied. Square pulses, 0.5 msec in duration, were delivered through stainless‐steel electrodes implanted in the VIIIth nerve. The stimulus intensity was randomly varied and the amplitude of the cortical potential was measured from a storage oscilloscope in a double blind manner. The amplitude at first rose sharply and then plateaued as the current intensity was further increased. The intensity function for electrical stimulation was different from that usually observed for acoustical stimulation in two respect. (1) For similar increases in stimulus intensity, a greater increase in the amplitude of the evoked potential was observed with electrical stimulation than with acoustical stimulation. This suggests the use of loud sound in behavioral transfer tests between acoustical and electrical stimulation of auditory centers. (2) Increases of stimulus intensity beyond that needed to produce plateau levels caused a reduction in the evoked potential amplitude with acoustical stimulation, but no reduction was observed with eleetrical stimulation. These data suggest that the reduction observed at high intensities of acoustical stimulation is due to a cochlear process, most probably the cochlear microphonic. [Supported in part by the National Institute of Neurological Diseases and Stroke and the Deafness Research Foundation.]