BACKGROUND: Music therapy is one of the most frequently used complementary therapies in different palliative care settings. Despite its long tradition and high acceptance by other health-care professionals, evidence on the effectiveness of music therapy interventions for terminally ill patients is rare. Recent reviews and health-care reports consistently point out the need of music therapists to provide an evidence-based rationale for their clinical treatments in this field. Therefore, the present study evaluates the psychological and physiological response of palliative care patients to a standardized music therapy relaxation intervention in a randomized controlled trial. METHODS/DESIGN: A sample of 84 participants from a palliative care unit in Heidelberg is randomized to either two sessions of music therapy or two sessions of a verbal relaxation exercise, each lasting 30 minutes. The music therapy sessions consist of live played monochord music and a vocal improvisation, the control group uses a prerecorded excerpt from the mindfulness-based stress reduction program containing no musical elements. Outcome measures include self-report data on subjective relaxation, well-being, pain intensity, and quality of life, as well as continuous recording of heart rate variability and blood volume pulse as indicators of autonomous nervous system functioning. DISCUSSION: To our knowledge, this study is the first clinical trial in Europe and one of very few randomized controlled trials worldwide to systematically examine the effects of music therapy in palliative care. TRIAL REGISTRATION: German Clinical Trials Register - DRKS00006137.