The purpose of this study is to determine the effect of Acceptance and Commitment Therapy (ACT) in groups on functional level, emotional problems, and use of health care in patients with severe health anxiety in a randomized, controlled design.

Health anxiety disorder or Hypochondriasis is a prevalent somatoform disorder, but a rarely used diagnosis in clinical practice despite studies having reported prevalence between 0.8-9.5% in primary care (Fink et al, 2004). As a consequence, the disorder is rarely treated.

The lack of valid, reliable, and generally accepted diagnostic criteria has been a major obstacle in clinical practice and Hypochondriasis studies, which causes problems particularly in distinguishing Hypochondriasis patients from other patients presenting with medically unexplained symptoms or functional symptoms.

In 2004, the investigators introduced a radically revised definition of Hypochondriasis. Hypochondriasis is viewed as a stigmatizing label, and the designation health anxiety has been suggested as replacement. This new diagnosis is empirically established. The essential feature of health anxiety is that the patients present with cognitive symptoms such as unfounded worrying about their health. In contrast to other somatoform disorders, the patients are not necessarily plagued by physical symptoms.

The new diagnostic criteria include the symptom 'obsessive rumination about illness' plus at least one of the symptoms 'worry or preoccupation with fears of harboring an illness or with bodily functions', 'suggestibility or autosuggestibility', 'an unrealistic fear of being infected or contaminated', 'an excessive fascination with medical information', or 'fear of taking prescribed medication'.

In the current study, health anxiety is diagnosed by use of newly introduced empirically established positive criteria for Health anxiety (Fink et al, 2004).

Most patients with health anxiety disorder receive the majority of their care in primary care settings. They are often unhappy with the services they receive, and primary care providers often feel unprepared to address symptoms that primarily appear functional.

During the past 5 years, the investigators have treated patients suffering from severe functional disorder (i.e. Bodily distress syndrome or Somatization disorder) in randomized controlled trials (RCTs) - at the Research Clinic. The investigators reject many patients suffering from health anxiety, who have no other treatment opportunities, and there is an impending need for treatment opportunities. The investigators research group has done research in epidemiology, psychopathology and diagnostics of Health anxiety, and the investigators are part of international networks regarding the revision of the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders V (DSM-V) and the International Classification of Diseases 11 (ICD-11).

RCTs have shown that Cognitive Behavioral Therapy (CBT) has effect on health anxiety (Barsky & Ahern, 2004; Greeven et al., 2007), and one of the trials also showed effect of anti-depressant medication (Greeven et al., 2007).

In general, the treatment of health anxiety is sparsely investigated both as to psychotherapy and medical treatment.

The investigators wish to examine the effect of Acceptance and Commitment Therapy (ACT) in groups on functional level, emotional problems, and use of health care in patients with severe health anxiety in a randomized, controlled design.

Health anxiety disorder is a burden for the sufferers and costly for society due to lost working years because of early onset of the disorder and high health care costs. The development of evidence-based treatment offering these patients the same professional treatment as patients with other disorders may lead to better quality of life for the patients and reduction in health care costs.

Inclusion Criteria:

1. Whiteley-7 score on 21,4 or more (scale 0-100 score points).
2. Severe health anxiety (diagnosed by SCAN interview).
3. Age 20-60 years
4. Patients of Scandinavian origin who understand, read, write and speak Danish.
5. No lifetime-diagnosis of psychoses, bipolar affective disorder or depression with psychotic symptoms (ICD-10: F20-29, F30-31, F32.3, F33.3)
6. In case of a co morbid functional or other psychiatric disorder health anxiety must be the dominating problem.

Exclusion criteria:

1. Another severe psychiatric disorder or if the patient is suicidal.
2. Abuse of narcotics or alcohol and (non-prescribed) medicine.
3. Pregnancy.
4. No informed consent.