The complicated labyrinthine structure of the vestibular sense organs make difficult to get normally fixed cytoarchitecture of the vestibular sensory cells. Keeping the normal intracellular organells are mandatory for the study of the early ultrastructural changes of the inner ear. Adequate perfusion of the fixative into the vestibular system is not easy due to the relatively narrow perilymphatic space of the canals and the small perilymph volume. To establish a proper vestibular fixation, three different methods of fixation with different fixatives were applied to the 16 guinea pigs and studied with the transmission and scanning electron microscope. The cardiac perfusion group which were prefixed with 2% paraformaldehyde-2.5% glutaraldehyde showed the mitochondrial degenerations in the upper part of the vestibular sensory cells. But the myelinated vestibular nerve fibers under the basement membrane showed normal architecture. Decapitation immersion fixed group which were prefixed with 3% glutaraldehyde prefixed specimens showed the most severe degeneration of the mitochondria in the cytoplasm and nerve terminals. 1.5% osmium tetroxide single fixed specimens in vivo and immersion showed normal cytoarchitectures and the normal preservation of the intracellular organells. In contrary to the in vivo fixation, the decapitation and immersion fixed specimens showed the multiple cytoplasmic protrusions of the sensory cells toward endolymphatic space adjacent to the stereocillia. Degenerated myelin heath of the vestibular nerve fibers were observed in the osmium tetroxide single fixed specimens probably due to slow speed of penetration of the osmium tetroxide into the deep seated nerved fibers. The best result of the vestubular sensory cells fixation was obtained from the 1.5% osmium tetroxide single fixation in vivo without any aldehyde prefixatives. But in vivo fixation needs time consuming procedures and give more chance to expose of the toxic osmium tetroxide tetraoxide to the examiner, whereas the decapitation immersion might be promising for the study of the sensory and supporting cells which were located superficially toward the endolymph space of the vestibular sensory organ. To avoid cytoplasmic protrusion, the specimens for the surface study of the sensory cell should be fixed in vivo by osmium tertroxide.