Hormonal therapies for cancer are often viewed as a gentler option than many other cancer treatments, but is low toxicity an accurate perception of patients' experiences? Side effects tend to be described as minimal or well tolerated, yet published symptoms from hormonal therapy vary considerably in their descriptions and frequencies. Previous research has highlighted under-reporting of side effects by clinical staff so as part of a wider study examining tamoxifen and goserelin treatment as adjuvant therapy for breast cancer, treatment-related symptoms documented in medical notes were compared with those that patients reported during a research interview. There was a significant difference in the frequency of many side effects reported by the two methods in this study. Sixty four out of 72 (89%) women who had received adjuvant tamoxifen or goserelin had side effects recorded in their medical notes, compared with 74/75 (99%) reporting side effects at interview. We compared the published frequencies of commonly reported symptoms with those found ourselves. The discrepancies between patient-reported and clinician-recorded (usually from clinical trial data) symptom profiles were similar to those found in our study. Without accurate comprehensive side effect profiles for hormone therapies, prospective patients cannot make informed judgements on proposed treatments.