Applying evidence-based medicine to complementary medicine (CM), which includes such therapies as acupuncture, chiropractic, hypnosis, and herbal medicine, seems at first contradictory. CM is often defined as techniques for which no evidence of benefit exists (or as a speaker at a recent Cochrane Colloquium put it, “medicine is either scientific or complementary”) But many of the interventions used by conventional clinicians have little scientific support. Conversely, evidence from randomised trials supports some interventions commonly described as CM. Use of this type of medicine is increasing in health care: About 10% of the U.K. population visits a CM practitioner each year (1), and about 40% of U.K. general practices offer their patients access to CM services through the National Health Service (NHS) (2). Thus, CM constitutes an important area for the implementation of evidence-based medicine for better patient care.