Hypochondriacal personality disorder diagnosed according to the Personality Assessment Schedule, a structured clinical interview, was related to outcome after 2 years and 5 years in a randomized, controlled trial of treatment of generalized anxiety, panic, and dysthymic disorders. Seventeen individuals (9%) from a population of 181 patients had hypochondriacal personality disorder and they experienced a significantly worse outcome than other patients, including those with other personality disorders, in terms of symptomatic change and health service utilization. This lack of improvement was associated with persistent somatization in hypochondriacal personality disorder. The results give further support to the belief that hypochondriacal personality disorder is a valid clinical diagnosis that has important clinical correlates, but further work is needed to establish the extent of its overlap with hypochondriasis as a mental state disorder.