The P-1 trial of tamoxifen versus placebo for breast cancer prevention in high-risk women provided proof of the concept that chemoprevention was effective. The approval of tamoxifen for this indication in 1998 provided a pharmaceutical agent as an alternative to bilateral mastectomy and/or oophorectomy for women at high risk. Although for some women and their physicians this was a welcome alternative, fear of toxicities from tamoxifen has been a major barrier to its use. Four trials evaluating the role of raloxifene in breast cancer prevention have resulted in the recent approval by the US Food and Drug Administration for postmenopausal women with osteoporosis or at high risk of breast cancer. It has a more favorable toxicity profile than tamoxifen and provides an alternative for postmenopausal women.