The hereditary breast/ovarian cancer syndrome is responsible for approximately 5% of all breast cancers and 10% of all ovarian cancers. Although this accounts for a small portion of these diseases, much attention has been focused on this syndrome because of the abundance of research in this area. The majority of the hereditary breast/ovarian syndrome can be attributed to germ-line mutations in the BRCA1 and BRCA2 genes. Reliable screening techniques for these mutations have been developed and are readily available in clinical practice. For patients who are thought to have the hereditary breast/ovarian cancer syndrome based on family history or genetic testing, options exist for either intensive screening or prophylactic surgery. This review will discuss the mechanisms by which mutations in the BRCA genes lead to the development of cancer, the limitations of currently available screening techniques, and the efficacy of prophylactic surgery. In general, prophylactic oophorectomy can be performed laparoscopically as an outpatient procedure, carrying as its main drawback the associated consequence of surgical menopause. Prophylactic mastectomy is quite effective in reducing the risk of breast cancer but is a more extensive surgical procedure and results in disfigurement. For any given patient, the best estimates of individual risk of breast or ovarian cancer should be weighed against the benefits of prophylactic surgery and the patient's personal wishes.