This study has shown that electrical stimulation of the auditory nerve in the cat at a certain rate will not reproduce the same firing patterns in the cells of the superior olivary complex as a tone of the same frequency. This occurred because the electrical stimulus probably produced synchronous firing of all the auditory nerve fibers, and the inhibitory mechanisms of the cochlear nucleus prevented activation of the auditory cells for all stimulus rates greater than 200/sec. On the other hand, a few cells were recorded in the medial superior olive which gave on- and off-responses to a tone and this firing pattern was reproduced with an electrical stimulus. Although electrical stimulation could not cause sustained excitation of cells, inhibition of spontaneous activity occurred for the duration of the stimulus in a number of cases. This was considered to be due to the effect of efferent stimulation of the olivocochlear bundle on spontaneous activity arising from the cochlea. Bipolar electrical stimulation of the cochlea was also carried out and this excited some cells in the superior olivary complex with characteristic frequencies in the middle to high frequency range. It was not possible to be certain, however, whether this was due to electromechanical stimulation or direct excitation of auditory nerve endings.