Machine learning and artificial intelligence, along with the algorithms that underpin them, hold great promise to improve health-care decision-making and biomedical innovation. But, as these powerful tools become an integral part of our lives, they pose unique challenges in areas of personal health-care information storage and use. What kinds of solutions could these technologies enable? What do patients and the general public need to understand—and consent to—about how their data is being used? What are the potential ethical and security downsides and pitfalls?