In postmenopausal women with hormone-dependent breast cancer, suppression of estrogen biosynthesis by endocrine therapy is preferred to combination chemotherapy with agents such as doxorubicin and paclitaxel. Although chemotherapy has comparable efficacy, it is frequently associated with unpleasant adverse effects. This is a particularly important consideration in patients with incurable metastatic disease, for whom improving quality of life is the primary goal of treatment. Tamoxifen remains the antiestrogen of choice, but is known to affect other tissues and may be associated with endometrial tumours. Pharmaceutical companies are working to develop hormonal treatments for breast cancer with improved short- and long-term tolerability and greater tissue specificity. One class of drugs likely to succeed tamoxifen as the preferred first-line treatment is the aromatase inhibitors. Three studies presented at the 25th Congress of the European Society for Medical Oncology [Hamburg, Germany; October 2000] compared nonsteroidal aromatase inhibitors with tamoxifen.