This chapter explores the nature of somatisation, describes the epidemiology, and outlines research and clinical issues. Psychiatric classification systems have included the specific disorder of somatization, as well as other disorders of unknown prevalence and questionable validity. Other important categories from a clinical perspective, such as chronic pain disorder, have major impacts on health care utilization across a wide range of disciplines. The vulnerability to somatic distress is not likely to occur simply secondarily to a general liability to the common forms of anxiety and depression. Primary psychogenic pain disorder is relatively rare. The avoidance response to pain often results in complex and even bizarre pain behaviors which are relatively common in pain-unit patients. Patients are particularly unlikely to comply with cognitive-behavioral approaches if they feel that such strategies will just result in their symptoms worsening, unless the physician also provides relevant symptom relief.