Acupuncture, a component of the health care system of China that can be traced back at least 2500 years, describes a family of procedures involving stimulation of anatomical locations on the skin by a variety of techniques. In November 1997, the National Institutes of Health conducted a consensus conference during which a panel of experts convened to discuss the scientific evidence regarding acupuncture. The panel concluded that acupuncture is an effective treatment for several medical conditions and described biochemical and physiologic mechanisms that begin to explain these effects. This presentation summarizes the evidence of the clinical efficacy of acupuncture and is divided into three segments. The first segment presents an overview of evidence-based medicine, the second segment summarizes the current evidence from systematic reviews of acupuncture, and the third segment looks to the future by proposing a stepwise method for designing phase I, II, and III acupuncture clinical trials.