This report presents the theoretical basis and some evidence to support the concept that most back, neck, and shoulder pain is due to a psychophysiological process in muscle and nerve tissue known as tension myositis. Descriptive data on age, past history of associated psychosomatic disorders, mode of onset of pain, patterns of pain location and tenderness, the latter considered the hallmark of tension myositis, and certain neurological correlates, suggest that it is the major cause of back pain rather than structural aberrations of the spine. It is suggested that success or failure in the conventional treatment of back pain is evidence for a psychosomatic process, via the placebo mechanism.