Serial electrochochleogram (ECochG) recordings were obtained over a long time span from 24 patients with Ménière’s disease showing dominant negative SP. The long-term fluctuation of responses (especially SP) was evaluated. Dominant -SP or abnormally increased SP/AP ratio has been unchanged over long periods in most operated or nonoperated patients. It is assumed that the generation of – SP dominance may chiefly result from the malfunction of hair cells, which may be caused by abnormal changes in inner ear fluids associated with endolymphatic hydrops or by other unknown disturbances in the cochlea. The mechanical factor of basilar membrane displacement can hardly be considered as a main cause of SP abnorm