We present anxiety buffer disruption theory (ABDT) and provide a review of current evidence regarding the theory. ABDT is an application of terror management theory to explain diverse reactions to traumatic events and the onset and maintenance of posttraumatic stress disorder (PTSD). It posits that PTSD results from a disruption in one's anxiety-buffering mechanisms, which normally provide protection against anxiety in general and death anxiety in particular. The disruption of these mechanisms leaves the individual defenseless in the face of overwhelming anxiety, which leads to the major symptom clusters of PTSD: re-experiencing, hyper-arousal, and avoidance. According to ABDT, because of the disruption in their anxiety-buffering mechanisms, individuals with PTSD symptoms do not respond to mortality reminders in the defensive ways that psychologically healthier individuals do. We review four sets of studies conducted in four different cultures and with people who have experienced different types of trauma, which reveal this atypical response pattern and lend support to ABDT.