Whether or not one believes that the Medicare Prescription Drug, Improvement, and Modernization Act (MMA) in fact improves or modernizes Medicare, the legislation obviously changes the program radically. The extent and nature of these changes make the MMA the most important piece of health care legislation to be adopted by Congress to date in this young millennium. The MMA also contains what are arguably the most important amendments to the Medicare program since its creation. This Essay first describes the identifying characteristics of the current Medicare program, then examines the significant changes that the MMA makes in the program, and finally discusses the importance-and danger-of these changes.