Endocrine therapy remains important in the adjuvant treatment of pre- and postmenopausal women. Adjuvant ovarian ablation with or without tamoxifen produces effects which are equivalent to those of CMF (cyclophosphamide, methotrexate and 5-fluorouracil) chemotherapy in premenopausal women with oestrogen receptor (ER) and/or progesterone receptor (PgR) positive breast cancer. Tamoxifen alone is also effective in these women. Concurrent use of tamoxifen and ovarian ablation may be even more effective, but more studies are needed. Tamoxifen remains a standard adjuvant therapy for postmenopausal women with ER and/or PgR positive tumours. Current information supports the use of 5 years of tamoxifen but additional studies comparing 5 years to longer duration are ongoing. The aromatase inhibitor (AI) anastrozole has now been demonstrated to be better than tamoxifen in preventing recurrence in early reports from the Arimidex vs Tamoxifen And the Combination (ATAC) Trial. Ongoing trials of this and other AIs before, after, concurrent with, or substituted for tamoxifen in the adjuvant setting may soon revolutionize our approach for postmenopausal women. Adjuvant bisphosphonates have been shown to reduce the incidence of bone metastases and improve survival in two of three published adjuvant trials and are being further studied. Her-2 neu status is being explored as a predictive factor for selection of endocrine therapy, but is not yet considered standard for this purpose.