Severe health anxiety (illness anxiety disorder) or hypochondriasis, according to the psychiatric classification system ICD-10, is characterized by preoccupation with fear of having a serious illness, which interferes with daily functions and persists despite medical reassurance. Clinical significant health anxiety is prevalent in primary care with 0.8-9.5%, and has a lifetime prevalence of 5.7% in the general population. It is a disabling disorder, associated with extensive use of health care services and occupational disability.