Aromatase inhibitors (AIs) have largely replaced tamoxifen as adjuvant hormonal therapy for postmenopausal women with early breast cancer. While tamoxifen is effective in reducing breast cancer recurrence and mortality, recent data indicate two peaks of early, mostly distant metastatic recurrences in patients receiving tamoxifen, and AIs have proven more effective in reducing recurrence. As distant recurrence has been associated with poorer survival and death, reduction in this type of early recurrence event may lead to improved survival over the long term. Recent data from major clinical trials are beginning to bear out this contention.