BRCA1 and BRCA2 breast cancer predisposition gene mutation carriers are at markedly increased risk of breast and other cancers. The consideration of chemopreventative options will depend on the cancer site and age-specific penetrance curve. Most chemoprevention studies to date have investigated the role of endocrine intervention in women at increased risk of breast cancer, and study results are conflicting. At the present time, there is uncertainty regarding whether endocrine intervention, particularly with tamoxifen, is as effective in BRCA1 and BRCA2 mutation carriers as in other women who are at increased risk of breast cancer because of hormonal factors or genes with moderately conferred cancer risks. Furthermore, if chemoprevention were needed for at least 10 years to produce an effect, new chemoprevention agents will need to be developed for women in their 30s, as the breast cancer risk curves are steepest between 40 and 50 years of age. Consideration is now being given to types of chemoprevention in this younger age group. There is also an increased risk of other cancers (in particular ovarian cancer and, in men, prostate cancer), and considerations regarding chemoprevention will have to encompass cancer at these sites.