Experiencing traumas during childhood can have a major impact on the emotional, behavioral, cognitive, social and physical functioning of children. Mental health professionals have long been aware of the psychological effects of traumatizing experiences and a common diagnosis in such cases is Posttraumatic Stress Disorder (PTSD) as defined in DSM-IV-TR (APA 2000). However, childhood experiences can be so complex that they give rise to more complex reactions than those captured in the PTSD diagnosis. But even if we recognize the warning signs of a childhood trauma and correctly diagnose the post-traumatic stress, we still need to understand the neurobiological effects of trauma in order to effectively treat its consequences. This article reviews the scientific literature focusing on traumatic experiences in children. The authors intend to offer an understanding of complex traumas, with a particular focus on its effects on brain functioning. Studies using magnetic resonance imaging (MRI) found reduced hippocampal volume in neglected children (B. Perry, 1997); a diminished hippocampal size may be either a consequence of trauma exposure or a risk factor for the development of psychiatric complications following trauma exposure. Modern research is stressing major alterations of complex neurobiological systems of processing basic information and of mediating autonomic, immune and endocrine defensive reactions. In the same time, the authors explore the existing strategies which promote recovery for traumatized children as well as the psycho-pedagogical implications. This knowledge can assist professional helpers in order to better identify, understand, support and empathise with traumatised children.