Information about the reasons for non-adherence among breast cancer patients taking tamoxifen is essential for the development of interventions that may increase adherence. The present study investigated treatment experiences and perceptions among women taking tamoxifen and how these related to adherence behaviour. Hundred and ten women completed questionnaires including the Women's Health Questionnaire, Hot Flushes and Night Sweats Questionnaire, Beliefs about Medicine Questionnaire and a self-report measure of adherence. Non-adherers were more likely to report a belief that there was nothing to be gained from taking tamoxifen whereas adherers were more likely to report that tamoxifen would stop them from developing breast cancer. The main reason for not taking tamoxifen was reported to be side effects. There were no differences between adherers with regard to the strategies used to remember to take tamoxifen or with regard to the time of day tamoxifen was taken. The results have implications for the role of health professionals in informing patients of the purpose of their treatment and for the development of symptom-management interventions for this patient group.