The hidden Jewish children represent the last survivors of the Holocaust and a specific population. They have not been recognized as Holocaust survivors until the 80-90 and have internalized silence as a survival strategy that has entailed a difficulty to share their story. The many traumatic experiences at an early age have increased their difficulties to understand and give a meaning to their trauma. Moreover, persecution and fear of being discovered during the war have severely impeded their sense of security. The many early separations they went through during and after the war have been detrimental to their emotional life. Finally, concealing their Jewish identity led them to experience a profound change of identity at a time they only began to construct themselves. This thesis aims to study qualitatively and quantitatively the long-term impact of early trauma experienced by this population. Seventy-two former hidden Jewish children were encountered. We studied their experiences and the organization of their traumatic memories 65 years after the Holocaust. We then showed that the events experienced during the war have sometimes become traumatic in the aftermath when memories were reactivated by a subsequent event which gave them a new meaning. We underlined that their trauma could be constructed in a four-step sequence of potentially traumatic experiences: 1) separation from parents under threat of life, 2) separation from foster-parents after the liberation, 3) a much later separation of a normally much lesser intensity like children leaving home or a divorce that triggers symptoms of various kinds, and finally 4) confrontation with the public recognition of their state as child survivors of the Holocaust, which opens old wounds but also offers the possibility to integrate early experiences into their life story. Finally, we studied the symptoms of PTSD and the cognitive strategies of 51 former hidden Jewish children. Our results were compared with a control population of non-Jewish individuals who also ...