The Dangerous and Severe Personality Disorder (DSPD) initiative in England and Wales provides specialized care to high-risk offenders with mental disorders. This study investigated the predictive utility of personality traits, assessed using the Psychopathy Checklist-Revised (PCL-R) and the International Personality Disorder Examination, with 44 consecutive admissions to the DSPD unit at a high-security forensic psychiatric hospital. Incidents of interpersonal physical aggression (IPA) were observed for 39% of the sample over an average 1.5-year period following admission. Histrionic personality disorder (PD) predicted IPA, and Histrionic, Borderline, and Antisocial PDs all predicted repetitive (2+ incidents of) IPA. PCL-R Factor 1 and Facets 1 and 2 were also significant predictors of IPA. PCL-R Factor 1 and Histrionic PD scores were significantly associated with imminence of IPA. Results were discussed in terms of the utility of personality traits in risk assessment and treatment of specially selected high-risk forensic psychiatric patients in secure settings.