Preventive health care aims to delay the onset of illness and disease and to prevent untimely and premature deaths. But the theory and rhetoric of prevention do not deal with the problem of how such health care applies to people who have already exceeded an average lifespan. In recent years, concerns about equity of access to treatments have focused on ageism. As a result, preventive interventions are encouraged regardless of age, and this can be harmful to the patient and expensive for the health service. In rapidly ageing populations, we urgently need to reappraise the complex and uncomfortable relations between age discrimination, distributive justice, quality, and length of life.