In the face of managed care and market economies infringing on the practice of medicine, reducing its autonomy and determining the moral guidelines for medical practice, many physicians are calling out for a return to what is perceived as a traditional medical ethic. Many religiously motivated critics of certain modern developments in medicine have made similar appeals. These calls are best understood as an attempt to define medicine as a practice that is necessarily ethical in nature, a practice the moral basis of which is internal to that practice. This article examines and assesses this definition of medicine in reference to Aristotle's division of human undertakings into three distinct categories: theory, poieisis (i.e., production), and praxis. It is concluded that medicine can be understood as a praxis (as opposed to a theory or production, both of which are morally neutral), because the practice of medicine, and all of its constitutive acts, can only be explained and assessed in reference to health, which is itself a final good and hence of moral value. Such an understanding would immunize medicine against usurpation by the free market. However, by the same token it would also dissociate medicine from all other moralities external to it, including those grounded in faith and religion.