OBJECTIVE To report hearing results in Swedish women with Turner's syndrome (TS), describe the recommendations of the Otologic Section of the Swedish Turner Academy for handling these patients and discuss the effect of estrogen on hearing in animals. METHODS Audiometric and karyotype tests were performed in 325 Swedish women with TS. A questionnaire was completed by 143 females with TS. Immunohistochemical staining of inner ear specimens was undertaken using antibodies against estrogen receptors in both human fetuses with TS and middle-aged women. Temporal bones obtained from various animal species were also studied immunohistochemically. RESULTS A total of 61% of the women had suffered from otitis media. A senorineural dip in hearing could be observed as early as the age of 6 years, progressed over time and was related to karyotype. The results of the questionnaire revealed that hearing impairment was rated as the fourth most serious problem associated with TS. The immunohistochemical study confirmed that estrogen receptors are present in the inner ear of humans. The animal experiments showed that estrogen receptors were present at almost equal amounts in rats, mice, TS mice, beta knockout mice and ovariectomized rats and at the same localization as in the human inner ear. CONCLUSIONS Both the senorineural dip in hearing and the karyotype can be used to predict the future course of hearing problems in TS patients. Estrogen may have an effect on hearing loss in TS patients but this phenomenon requires further investigation.