Abstract Health anxiety is usually transient or easily dealt with by appropriate medical reassurance and/or treatment (Figure 1). In some cases, even though no physical illness has been detected, the patient is not reassured and their health anxiety continues. This may occur because of the patient's cognitions (Figure 2), the doctor's failure to provide adequate reassurance, or both. In extreme cases the patient may fulfil the diagnostic criteria of one of the somatoform disorders, primary hypochondriasis. Over the past 20 years, hypochondriasis has been accepted as a disorder in which the central feature is a persistent tendency to make catastrophic misinterpretations of innocuous physical symptoms and signs as evidence of physical illness (Figure 2). More recently it has been suggested that hypochondriasis may be more appropriately classified as an anxiety disorder (Warwick and Salkovskis, 1990) – severe health anxiety. The psychopathology of severe health anxiety is discussed in detail on pages 76–9. It used to be accepted that there was no treatment for severe health anxiety; however, there are now published reports of successful cognitive-behavioural treatment (CBT) for this distressing condition (Warwick et al., 1996; Clark et al., 1998), which will provide the focus for this contribution.