Transplantation of exogenous stem cells has been proposed as a treatment to prevent or reverse sensorineural hearing loss. Here, we investigate the effects of transplantation of adult human olfactory mucosa-derived stem cells on auditory function in A/J mice, a strain exhibiting early-onset progressive sensorineural hearing loss. Recent evidence indicates that these stem cells exhibit multipotency in transplantation settings and may represent a subtype of mesenchymal stem cell. Olfactory stem cells were injected into the cochleae of A/J mice via a lateral wall cochleostomy during the time period in which hearing loss first becomes apparent. Changes in auditory function were assessed 1 month after transplantation and compared against animals that received sham injections. Hearing threshold levels in stem cell-transplanted mice were found to be significantly lower than those of sham-injected mice (p < .05) for both click and pure tone stimuli. Transplanted cells survived within the perilymphatic compartments but did not integrate into cochlear tissues. These results indicate that transplantation of adult human olfactory mucosa-derived stem cells can help preserve auditory function during early-onset progressive sensorineural hearing loss.