Objectives@#. The relationship of estrogen (the primary femalesex hormone) with hearing function has been studied in both humans and animals. However, whether estrogen levels affecthearing remains uncertain. Therefore, in this study, we investigated changes in the vulnerability of hearing to acoustic overexposure in ovariectomized femalerats. @*Methods@#. Eighteen 8-week-old femaleSprague-Dawley rats were separated into four groups as follows sham ovariectomy (OP), OP only, and OP treated with low (10 µg/kg) or high doses (100 µg/kg) of estrogen. Rats in the estrogen replacement groups were given two intraperitoneal injections. Hearing thresholds were measured before noise exposure, and at 1 day and 2 weeks after exposure. @*Results@#. The hearing thresholds of the sham OP and OP-only groups were not significantly different. However, both estrogen groups showed a lower threshold shift than the OP-only group. Histological immunostaining analyses showed that haircell loss in the 32 kHz region was more severe in the sham OP group than in the OP-only group. Furthermore, there was little or no haircell loss in either estrogen replacement group and significantly more haircell loss in the OP-only group. @*Conclusion@#. These results suggest that estrogen replacement may reduce the vulnerability of hearing to noise exposure in menopausal women.