Within the past decade, scientists have reported the discovery of potent genes that predispose to major cancers, including breast, ovarian, and colorectal cancer. The discovery of human cancer susceptibility genes is important for fundamental research into the cause of cancer. In addition, these discoveries will certainly have profound implications for the prevention and diagnosis of breast cancer. However, it is not yet clear whether and to what extent cancer susceptibility genes will alter the treatment of cancer. While breast cancer is an important malignant disease in women, it is hoped that knowledge gained from the management of this common disease will provide a template for the approach to other malignancies, caused by hereditary factors. In this paper, we will review the state of knowledge about genes that predispose to breast cancer. Our focus will be to summarize the available information, addressing how genetic factors may alter the initial approach to cancer in the breast. We will concentrate on the surgical management of early breast cancer. Issues include the use of limited surgery with radiation (breast conservation), the approach to the opposite breast, and prophylactic mastectomy in patients at high risk.