The diagnostic criteria set for posttraumatic stress disorder (PTSD) has gradually evolved from DSM-III, to DSM-IV, to DSM-5. Besides a broadening of the event criterion for PTSD, the symptom domain now involves many different brain circuits and types of symptoms, including: fear and anxiety; anger and aggression; negative cognition and mood; hypo-arousal; and dissociative symptoms. The dissociative subtype of PTSD in DSM-5 is defined by the presence of depersonalization or derealization. However, the diagnostic criteria for PTSD also include dissociative flashbacks and dissociative amnesia. If these symptoms were included in the definition of the dissociative type of PTSD in future editions of the manual, then most cases of PTSD would be dissociative in nature, and non-dissociative cases would be a minority subtype. There does not appear to be any sound conceptual reason for excluding amnesia and flashbacks from the criteria for dissociative PTSD.