Tamoxifen is probably the most important drug in the history of the management of breast cancer and its development is a tribute to cross talk between laboratory scientists and clinical investigators. Its use as adjuvant therapy has led to a decrease of 20-30% in age-adjusted cause-specific mortality in the developed world and it is approved in the USA for the chemoprevention of breast cancer in high-risk women. The recent ATAC and IBIS trials have challenged the supremacy of tamoxifen. The present paper is a personal view of the implications for the future use of this drug in competition with the oral aromatase inhibitors. In the opinion of the author tamoxifen will probably remain the mainstay for adjuvant therapy of postmenopausal women with hormone-responsive disease, but maturation of the ATAC data may allow a choice in selected cases. Anastrozole looks like a competitor for the future but we may have to wait another 10 years to find out.