Precision medicine promises to deliver improved patient outcomes and lower health-care costs, potentially benefiting millions of patients and saving global healthcare systems tens or even hundreds of billions of dollars per year through improved efficiency, reduced misprescription and over-medication and better compliance. Precision medicine’s ultimate benefits may, however, be even wider than this, as people learn more about their own disease risks and are given tools that educate and empower them to become active partners in the management of their own health. By helping people to change their own behaviors to remain healthier and independently active for longer we will ultimately reduce the economic and social burden of avoidable chronic lifestyle diseases, and the dependence on social and clinical care, which are continually increasing the cost of care globally, across all developed and developing economies. Delivering the potential of precision medicine will however present a number of challenges to scientists, clinicians, technologists and healthcare systems.