The discovery of the first gene associated with hereditary breast cancer, BRCA1, was anticipated to greatly increase our understanding of both hereditary and sporadic forms of breast cancer, and to lead to therapeutic and preventive breakthroughs. Much has been learned during the past decade about the genetic epidemiology of breast cancer, the ethnic distribution and clinical consequences of BRCA1 and BRCA2 mutations, and the central role of DNA repair in breast cancer susceptibility. The ability to translate this knowledge into novel treatments, however, remains elusive.