Background: To the knowledge of this author, no known studies with equally large sample sizes have shown as low prevalence (0.4%) for histrionic personality disorder (HPD) as that of this one. As a literature review indicates that HPD suffers from low construct validity, this article will shed light on the low prevalence by analyzing the construct validity of HPD.Methods: Data was obtained from twelve different Norwegian day treatment centres, comprising 2289 patients treated for personality disorders. Information on personality disorders was gathered by Structured Clinical Interview for DSM-IV Axis II Diagnoses (SCID-II), in addition to measures on dysfunction, distress and interpersonal problems. The author did not participate in data gathering.Results: Although only 10 (0.4%) patients obtained HPD diagnosis, certain findings aided analysis of construct validity; (1) HPD diagnosis and fulfilment of HPD criteria indicated distress and dysfunction, (2) the HPD criteria were interrelated, but only marginally more related to HPD than to borderline personality disorder and to narcissistic personality disorder diagnoses, and (3) the eight HPD criteria were, by of exploratory and confirmatory factor analysis, divided into two factors.Conclusions: The HPD diagnosis in its current form seems to suffer from low construct validity, with implications for prevalence rates. Different possibilities as to which latent structures underlie the eight HPD criteria are discussed, and a tentative suggestion as to the shared properties between these structures is offered.