Nerve fibers with distinctive branching patterns have been demonstrated in guinea pigs by use of the Golgi stain. The cochlear nerve fibers in the basal turn tend to supply a limited segment of the basilar membrane and have most endings on a single row of hair cells. The efferent olivocochlear nerve fibers ramify in a manner which varies from base to apex. Some efferents which terminate on outer hair cells also give branches which course in the inner spiral bundle. Other nerve fibers were studied in the spiral lamina which did not penetrate into the organ of Corti.