Is the female sex steroid estrogen the key to preserved hearing in the aging human? It is well known that hearing loss is more profound in elderly males than females,regardless of noise exposure.Also,an age-related hearing decline starts much earlier in males,already after the age of 30,while in women,the decline does not start until the age of 50.This coincides with the menopausal transition in most women,when endogenous circulating levels of estrogen in the body are decreasing.It is also well known that women with Turner syndrome who are estrogen deficient suffer from early onset of age-related hearing loss already at the age of 35.Estrogen excerts its effect through two nuclear,estrogen receptors,estrogen receptor and which we have earlier showed to be present in the inner ear of mouse,rat and humans.If estrogen receptor is knocked out,we have demonstrated that a severe progressive hearing loss is present that leads to an early deafness in the mouse.Estrogen receptors are up and down-regulated in the inner ear depending on the stage of maturation,development and pregnancy.Actions of other sex-hormones,such as progesterone and testosterone must also be considered.Knowing how sex steroids can alter the hearing abilities might give us important clues as to how estrogen can preserve hearing in humans.In the presentation a summary of what is known up to day about hearing and estrogen will be given.