The vestibular ganglion cells of the rat were classified with regard to the cytoplasmic structure by light and electron microscopic observation. Light microscopy revealed four types of cells, depending upon the characteristics and distribution of Nissl granules. Electron microscopy gave a definite classification of these types by the arrangement and distribution of the rough surfaced endoplasmic reticulum and neurofilament. The characteristics ofthe ganglion cells were discussed in relation to the cell size and their neurotransmittingfunction.