Abstract This review deals with diagnostic problems in DSM-III-R hypochondriasis. A first category of problems is directly connected with the definition of hypochondriasis. The following topics are discussed: the distinction between hypochondriasis and hypochondriacal attitude, the personality aspects of hypochondriasis, and the role of medical findings in the diagnosis. This is followed by a discussion of problems as to the distinction between hypochondriasis and related disorders. This concerns the status of hypochondriasis as a primary or secondary disorder in depression and the relationship with anxiety disorders (especially panic disorder and obsessive-compulsive disorder [OCD]) and the somatization disorder. The DSM-III-R classification of hypochondriasis as a somatoform disorder is disputed. A third category of problems lies in the measurement of hypochondriasis. The scope and quality of the most frequently used questionnaires for measuring hypochondriasis are poor. In research, on the basis of a single questionnaire and without due consideration of medical findings, the diagnosis of hypochondriasis is applied too soon. Finally, it is briefly indicated that the lack of diagnostic clarity affects the way in which the patient is approached in clinical practice.