RESUMEN
Pain is the most complex human experience and the most frequent cause for which patients seek medical help. Whereas acute pain promotes survival by enabling the organism to avoid or escape harm, chronic pain is usually destructive physically, psychologically and socially. Pain reaches consciousness at the level of the thalamus, its localization requires the participation of the sensory cortex; the behavioural changes characteristic of pain are governed by the limbic system. The two vasoactive amines, serotonin and histamine, and the peptide bradykinin are ubiquitous enough to fill the role of biological chemical mediators of pain. The prostaglandins have an important role at the nociceptor level. The substance P and endorphins are involved in the transmission of pain information in the central nervous system. The recent development of multidisciplinary pain clinic affer a new approach in managing patients with chronic pain. The range and diversity of techniques currently used to relieve pain emphasize the unsatisfactory state in which surgery is placed. Acupuncture, as a form of treatment for pain, is greatly influenced by psychological factors