PURPOSE: Our aim was to examine in a prospective pilot study whether standard adjuvant treatments for breast cancer can adversely affect hearing. METHODS: Eight pre/peri-menopausal women with breast cancer had middle ear analysis (tympanometry) and pure tone audiometry conducted prior to and 6 months following Fluorouracil, Epirubicin, Cyclophosphamide (FEC) or FEC plus taxotere chemotherapy treatments. RESULTS: The mean hearing thresholds in both ears showed an elevation (that is a decline) post chemotherapy treatment at 6 and 8kHz of between 20 and 30dB, which is graded as a mild hearing impairment at the higher frequency range. There were individual differences in pattern and grade within the group. CONCLUSIONS: The variability noted in the data is more than that would be anticipated for test-retest variance, suggesting that the hearing impairments are complex but genuine. The most likely cause of the reduction in hearing sensitivity is a change in oestrogen levels resulting from the breast cancer treatments.