Fragmentary medical-epistemological thoughts are put forward in medical journals and books every day. But there is as yet no medical epistemology as an established area of inquiry. As a result, no methodology is available to instruct us about how to conduct medical epistemology. To establish a field of medical epistemology with well-identified problems, issues, and a specific methodology, requires an answer to the question: What is medical epistemology and what is it needed for?