The relaxation response is an integrated psycho-physiologic response originating in the hypothalamus that leads to a generalized decrease in arousal of the central nervous system. As such it is the physiologic antithesis of the stress response. This hypometabolic state is the foundation of many nursing interventions. Relaxation interventions have been taught for centuries. They include many theoretic and philosophic traditions and an array of specific strategies. The possible outcomes using relaxation response strategies in nursing practice are numerous and enable the patient to use the body's own innate mechanisms for health and healing. Thirty-seven studies of the efficacy of relaxation response interventions with adult patients are reviewed. Although numerous patient populations are addressed by the studies, some of which have methodologic problems, consistencies in the results suggest the effectiveness of the relaxation response in reducing hypertension, insomnia, anxiety, pain, and medication use across multiple populations, diagnostic categories, and settings. Recommendations for the use of relaxation responses in varied clinical settings are included.