OBJECTIVE: A 2-year study was undertaken to determine the frequency of multiple personality disorder among general adult psychiatric inpatients. METHOD: All individuals admitted to two 23-bed acute care wards in a teaching hospital in Winnipeg, Man., were screened with the Dissociative Experiences Scale. Individuals with prior diagnoses of multiple personality disorder were excluded. All subjects scoring 20 or higher on the Dissociative Experiences Scale were interviewed with the Dissociative Disorders Interview Schedule. Then subjects with a diagnosis of multiple personality disorder and comparison subjects were interviewed by a clinician who was blind to all research data. RESULTS: A total of 299 subjects completed the Dissociative Experiences Scale and 80 received a structured diagnostic interview. Ten subjects (3.3%) had clinically confirmed multiple personality disorder. CONCLUSIONS: If these results are replicated and accepted, multiple personality disorder will become a serious consideration in the differential diagnosis of many psychiatric patients.Abstract Teaser