BACKGROUND:There is a specific pathway named vestibulo-cochlear pathway runs through the inferior vestibular nerve to cochlea. vestibular neurectomy (V.N) is a well established procedure that is performed to control intractable Meniere disease. However, the function and the histopathological changes of the cochlea that could be occurred after vestibular neurectomy were not fully studied. OBJECTIVE:Experimentally test the effect of vestibular nerve neurectomy on the function and histopathology of the cochlea. EXPERIMENTAL PROCEDURES: The study was conducted on 20 normal male adult pigmented guinea pigs (Cavia porcellus). First, each animal was tested with Distortion Product Otoacoustic Emissions (DPOAEs) preoperatively then vestibular neurectomy (V.N) was performed on the right side through suboccipital modified retrosigmoid approach. We tested the DPOAEs postoperatively; After 8 weeks, Guinea pigs were euthanized the cochlea of guinea pig was processed for light microscope and transmission electron microscope examination to observe the outer hair cell count, and spiral ganglion cell density in the operated ear compared to contralateral non operated cochlea of the same guinea pig. RESULTS:There was a significant decrease in spiral ganglion cell density in the operated side compared to the non-operated side. However, there was no significant difference in outer hair cell count or DPOAEs between the two sides, except for a significant increase in DPOAEs at 2 KHz in the operated side. CONCLUSIONS:The results suggest that vestibular neurectomy may affect spiral ganglion cell density but not necessarily outer hair cell count or DPOAEs, and the relationship between these variables is complex and could be frequency-depende