The understanding of cancer at a molecular level and of the contribution of certain genetic mutations to the development of cancer is progressing at an unparalleled rate. Advances in technology and discoveries stemming from the Human Genome Project now provide the means to test individuals for the presence of mutations associated with some known hereditary cancer syndromes. Although many ethical, legal, and psychosocial issues associated with testing remain unresolved, predisposition genetic testing is having and will continue to have a significant impact on health care. Nurse practitioners will play a vital role in assessing clients for increased risk of developing cancer, educating clients about the availability of testing, making referrals for cancer genetic counseling and risk assessment, and providing follow-up care in the community for patients found to be at increased risk.