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When an event is perceived as life-threatening or as having the potential to cause serious bodily injury to oneself or others, an intense feeling of fear, horror or helplessness can arise and the memory process can be disrupted, leading to the development of post-traumatic stress disorder (PTSD). This pathology is characterized by three kinds of symptoms: (i) re-experiencing, which is probably the main PTSD symptom and refers to intrusive memories occurring in flashbacks and/or nightmares so invasive that PTSD sufferers feels as if they are reliving the sensory and emotional aspects as occurring in the present; (ii) avoidance, where sufferers try to avoid everything that may remind them of the traumatic event (thoughts, places, people, and other reminders of the trauma) and (iii) hyper-arousal, which includes hyper-vigilance, exaggerated startled reactions, sleep disturbances, and irritability. The purpose of this article is to review the current state of knowledge on memory disturbances and cerebral abnormalities that are central to the pathology’s importance. PTSD in adults is well documented, and a concise description of the impairment of traumatic event memory has been established, involving both enhanced memory for emotional aspects and decreased memory for contextual information. As for traumatic events, memory for everyday events is also impaired in PTSD, with hypermnesia for negative information and lower memorizing of neutral information. Structural and functional abnormalities of brain areas involved in episodic memory (hippocampus), emotional memory (amygdala), and emotional regulation (medial prefrontal and anterior cingulate cortices) seem involved in memory disturbances observed in PTSD. We will describe the two main theories synthesizing current understanding of adult PTSD. In children, while the symptoms are well described, the lack of investigations hinders the accurate identification of a particular profile of memory dysfunctions and their cerebral substrates. However, we will review the few findings in this field.