In order to investigate the concept of hypochondriasis a questionnaire has been devised. Evidence of its validity and reliability has been presented. This has been followed by a principal component analysis. Three factors have been identified as reflecting three dimensions of hypochondriasis, viz: Bodily Pre-occupation", "Disease Phobia" and "Conviction of the Presence of Disease with Non-Response to Reassurance". These three factors are discussed in relation to the literature on hypochondriasis. Their nature lends support to those observations which have been based on clinical experience.