Background: By definition personality disorders (PD) are evident in adolescence and early childhood, but evidence for adult onset personality pathology following traumatic experience is much less clear. Aims: My primary objective was to investigate whether exposure to war trauma can lead to personality pathology in adults. Methods: Following a systematic review of extant literature on this topic, I conducted a case-control study in a war-affected region of southern Croatia. I recruited 268 participants: 182 cases who scored positively on the International Personality Disorder Examination scale (IPDE), and 86 controls who were IPDE negative. In addition to the IPDE, all participants completed Harvard Trauma Questionnaire, measures of mental health, social functioning, childhood trauma and childhood behavioural problems. I used a clinical interview to assess when personality-related problems started. Results: Cases (IPDE positive) were eight times more likely to report exposure to catastrophic trauma than controls. This association increased after adjustments for demographic factors (OR= 10.1, 95% CI 5.0 to 20.4). Among 182 IPDE positive participants, 65 adults (35.7%) had no history of pre-trauma personality pathology suggesting change in personality following their exposure to trauma in adulthood. When compared to the PD group, patients with adult onset personality pathology had poorer mental health, social functioning and similarly high rates of unemployment more than 15 years after trauma. They were three times more likely to meet criteria for personality traits across all three DSM-IV clusters (OR= 3.28, 95% CI 1.51 to 7.13). The most frequent personality traits reported were avoidant, borderline, schizotypal, schizoid and paranoid, but only schizotypal (75.4% vs. 47.3%) and schizoid traits (73.8% vs. 41.1%) were more prevalent among those with adult onset personality pathology compared to those with PD. Conclusion: People with no clear pre-trauma personality problems can develop long-term personality pathology following exposure to severe trauma in adulthood. These findings have implications for future research, clinical practice and the classification of personality disorder.