Evidence-based medicine (EBM) is the integration of best external evidence with clinical expertise and patient values. The full-blown practice of EBM comprises the following 5 steps; converting the need for information (e.g. diagnosis, prognosis, therapy, and prevention) into an answerable question (step 1), tracking down the best evidence with which to answer that question (step 2), critically appraising that evidence for its validity, impact, and applicability (step 3), integrating the critical appraisal with our clinical expertise and with the patient's unique biology, values and circumstances (step 4), and evaluating our effectiveness and efficiency in executing steps 1 to 4 and seeking ways to improve them both for next time (step 5). Concerning the step 1, it is often difficult to define "exposure" and "outcome" clearly in the field of psychosomatic medicine. For my clinical and research experience under Herbert Benson, M.D at Mind/Body Medicine, Harvard Medical School (1998-2001), definitions of stress and relaxation were quite elaborate tasks to assess the effects of stress management program in the treatment of patients with mind/body distress (Nakao M, Fricchione G, Benson H, et al. Psychother Psychosom 70: 50-57, 2001). He used the word of "relaxation response" instead of "relaxation", and defined it as follows; "the relaxation response is the psychological and physiological opposite of the arousal or stress response, characterized by decreased metabolism, blood pressure, rate of breathing and heart rate in association with feelings of calmness and control." Although general interest in relaxation therapies is on the rise, research in this area does not seem to be growing at the same pace. The working group of the Cochrane library has just begun their work to accumulate literature concerning relaxation therapies for the management of essential hypertension in adults (Nicolson DJ, et al. The Cochrane Database of Systematic Reviews, Volume 1, 2006 [Protocol]). According to this recent report, relaxation therapies include autogenic training, cognitive therapy, behavioral therapy, meditation, guided imagery, biofeedback, progressive muscle relaxation, breathing exercises, and yoga. They identified five systematic reviews, one of which was published by us (Nakao M, Yano E, Nomura S, et al. Hypertens Res 26: 37-46, 2003). In our systematic review, 388 articles were initially selected for review of biofeedback treatment for essential hypertension, but only 22 articles met inclusion criteria for further review and meta-analysis, meaning that the remaining 366 articles did not have enough information based on the standardized quality assessment. Although psychosomatic medicine is comprised of different approaches including internal medicine, psychiatry, psychology, sociology, and behavioral medicine, it should be recognized and applied in the mainstream of medicine, and many researchers and practitioners are needed to be involved in establishing the EBM of psychosomatic medicine.