It is critical that public health advocates understand the structure of the Medicare program and the impact of the political process on Medicare's benefit set. This article provides an overview of the design of Medicare and its explicit exclusion of prevention benefits in the original legislation. We then provide a history of subsequent legislation authorizing coverage of specific prevention benefits over the last twenty years. We critique the current process in light of innovation in preventive services and the influence of politics in the decision-making. We conclude with a discussion of policy options to improve access to an appropriate range of evidence-based preventive services in Medicare within the context of new technology innovation and rising health care costs.