Breast cancer treatment has evolved greatly within the last 25 years. Tamoxifen was first introduced for the treatment of metastatic breast cancer in the 1970s and later became accepted as standard adjuvant therapy. The emergence of tamoxifen as first-line hormonal therapy for metastatic disease and in the adjuvant setting occurred due to its efficacy in achieving prolonged overall survival as well as improved disease-free survival, the latter of which improves the psychological and physical quality of life of the patient. Tamoxifen is currently being studied for the prevention of breast cancer. Completion of this important trial is eagerly awaited.