In metastatic breast cancer, orally-active, potent, selective third-generation nonsteroidal inhibitors and steroidal inactivators have shown superiority over tamoxifen, a selective oestrogen receptor modulator. In advanced breast cancer, aromatase inhibitors and inactivators are becoming established as the standard of care over tamoxifen in postmenopausal female breast cancer patients when hormonal therapy is indicated for first-line treatment. Emerging research evidence and ongoing clinical investigations look likely to further extend the use of these potent agents across several additional treatment settings in the management of breast cancer. Several multi-centre studies are underway examining the role of novel hormonal therapy in the adjuvant treatment of early breast cancer and other investigations will explore possible future applications of these potent antiaromatase agents, including breast cancer prevention.