Until the 1960s, pain was considered an inevitable sensory response to tissue damage. There was little room for theaffective dimension of this ubiquitous experience, and none whatsoever for the effects of genetic differences, pastexperience, anxiety, or expectation. In recent years, great advances have been made in our understanding of themechanisms that underlie pain and in the treatment of people who complain of pain. The roles of factors outside thepatient’s body have also been clarified. Pain is probably the most common symptomatic reason to seek medicalconsultation. All of us have headaches, burns, cuts, and other pains at some time during childhood and adult life.Individuals who undergo surgery are almost certain to have postoperative pain. Ageing is also associated with anincreased likelihood of chronic pain. Health-care expenditures for chronic pain are enormous, rivalled only by the costsof wage replacement and welfare programmes for those who do not work because of pain. Despite improved knowledgeof underlying mechanisms and better treatments, many people who have chronic pain receive inadequate care.