Hair cell regeneration is the fundamental method of correcting hearing loss and balance disorders caused by hair cell damage or loss. How to promote hair cell regeneration is a hot focus in current research. In mammals, cochlear hair cells cannot be regenerated and few vestibular hair cells can be renewed through spontaneous regeneration. However, Math1gene transfer allows a few inner ear cells to be transformed into hair cells in vitro or in vivo. Hair cells can be renewed through two possible means in birds: supporting cell differentiation and transdif-ferentiation with or without cell division. Hair cell regeneration is strongly associated with cell proliferation. Therefore, this study explored the relationship between Math1-induced vestibular hair cell regeneration and cell division in mammals. The mouse vestibule was isolated to harvest vestibular epithelial cells. Ad-Math1-enhanced green fluorescent protein (EGFP) was used to track cell division during hair cell trans-formation. 5-Bromo-2′-deoxyuridine (BrdU) was added to track cell proliferation at various time points. Immunocytochemistry was utilized to determine cell differentiation and proliferation. Results demonstrated that when epithelial cells were in a higher proliferative stage, more of these cells differentiated into hair cells by Math1gene transfer. However, in the low proliferation stage, no BrdU-positive cells were seen after Math1gene transfer. Cell division always occurred before Math1transfection but not during or after Math1transfection, when cells were labeled with BrdU before and after Ad-Math1-EGFP transfection. These results confirm that vestibular epithelial cells with high proliferative potential can differentiate into new hair cells by Math1gene transfer, but this process is independent of cell proliferation.