Introduction: Post-traumatic stress disorder (PTSD) is a mental disorder that emerges due to severe stressful events including flood, earthquakes, war, aggression, etc. Due to the nature of their job, firefighters are at high risk of developing complications and psychiatric problems, including PTSD. The present study was carried out aiming to compare self-differentiation and neurosis among firefighters with and without PTSD. Methods: The PTSD checklist developed by Weathers et al. was distributed among 180 firefighters directly active in the fire of the Plasco building in Tehran, Iran, in 2017. From among these individuals, 30 people with and 30 without PTSD were selected randomly. The participants completed the Differentiation of Self Inventory (DSI) developed by Skowron and Dendy and the Neuroticism Scale of the Eysenck Personality Questionnaire (EPQ). Findings: There were no significant differences in terms of the components of emotional cutoff (EC) (F=0.973, P>0.05), emotional reactivity (F=0.404, P> 0.05), fusion with others (FO) (F = 0.338, P > 0.05), and I-position (F = 0.774, P > 0.05) between firefighters with and without PTSD. In addition, there were no significant differences in terms of neurosis between firefighters with and without PTSD (F= 0.034, P>0.05). Conclusion: Being in highly stressful circumstances for a long duration of time (about 10 days) and cognitive, emotional, and environmental factors seem to expose this statistical sample to PTSD. Moreover, in the firefighting recruitment process, complete medical examinations are performed, which can be the reason for the low and equal levels of neurosis and differentiation of self in all individuals with and without PTSD.
