The last decade has witnessed dramatic advances in our understanding of the molecular changes that underlie both the development of sporadic cancers and the inheritance of familial cancers. Several genes that predispose an individual to specific types of cancer have been isolated, providing the opportunity to identify people at high risk of developing cancer. This new knowledge has received considerable attention from the media, and referrals to geneticists, surgeons and oncologists, as well as requests for genetic testing, have risen markedly. However, many uncertainties exist about the clinical value of identifying carriers of mutations in cancer predisposing genes. Here we review the existing evidence concerning the management of people at increased risk of hereditary cancers, and discuss the implications for primary care. We focus on the more common inherited cancer syndromes, since they will have the greatest potential impact on clinical practice over the next decade. Furthermore, they offer a model of how information on the genetics of other cancers and common diseases may affect primary care in the future.