Objectives: Endolymphatic hydrops has been considered as an important histologic substrate of Meniere’s disease. A permanent displacement of the basilar membrane by increased endolymphatic pressure has been thought to be an explanation of hearing change. Direct observation of histological sections of temporal bones of human patients with Meniere’s disease, however, suggested that stereocilia and tectorial membrane decoupling would be more associated with pressure induced mechanical deformation of the organ of Corti rather than displacement of the basilar membrane. Methods:26 cochleae from 13 female pigmented ginea pigs were harvested. One cochlea per each animal was injected with artificial perilymph. The other one was used as control. After fixation, embedding and mid-modiolar section, specimens were viewed with microscope. Morphometric parameters of each rows and turns the organ of Corti such as area and height of the organ of Corti, height of tunnel of Corti length of outer hair cell and Deiters cell and angle between outer hair cell and outer hair cell were measured and quantified. Result:Average area and height of the organ of Corti were significantly smaller in apical turn of experimental group(P <0.05). length of outer hair cell and Deiters cell in apical turn were also significantly reduced in experimental group(P < 0.05). Angle between outer hair cell and Deiters cell was smaller in apex and 3rd turn of experimental group(P < 0.05). Conclusion:Results show that compression and deformation of the organ of Corti especially in apical turn is a prominent feature in acute endolymphatic hydrops model. We suggest that the deformation of the organ of Corti would be the primary cause of the hydrops induced decoupling of tectorial membrane and stereocilia rather than displacement of the basilar membrane.