Evidence-based medicine (EBM) has grown in popularity and prominence in the world of orthodox medicine since the 1980s. The focus of this article is on the process of developing practice guidelines (one type of EBM) and its effects upon chiropractic, a profession with a "philosophy, science and art" that is constructed upon divergent epistemological and methodological tenets (namely, the idea of "vitalism"). The EBM movement is conceptualized as part of a larger political economy surrounding the health care environment that creates a new set of imperatives for orthodox medicine, and also branches of alternative medicine that are in the process of professionalization. The quantitative, positivist and empiricist assumptions of EBM dictate which approaches to treatment and which clinical procedures are legitimate and perhaps reimbursable under systems of managed care. The ramifications of practice guidelines and its effects upon the intraprofessional segments of the chiropractic profession are also discussed.