Genetic testing is a powerful technology that enables prediction of future health status. Testing for cancer-predisposition genes provides information for both the individual and his or her family. The use of this information reaches beyond the medical sphere to the psychological, social, legal, and ethical. The important issues include informed consent, autonomy, confidentiality, justice, disclosure and non-disclosure, duty to warn, genetic discrimination, predictive genetic testing of children, preimplantation genetic diagnosis, and patenting of cancer-predisposition genes.