Following the humanitarian crisis caused by the Syrian war, the shortages in European Union’s reception system exposed numerous children to a prolonged period of transit within frontier countries (e.g., Italy), during which they were considered “invisible” and received no legal recognition and protection. This situation offered a unique possibility to study the psychological dimensions involved in the elaboration of trauma during a migratory journey characterized by the lack of reception services. The present study, conducted on a group of Syrian children (n = 271) in transit to Italy with their families while on their journey to Northern Europe, aimed to explore the mental health of this population, focusing on the impact of interpersonal trauma as risk factors and resilience as protection for children’s mental health outcomes. The children were assessed for dose of exposure to traumatic experiences, post-traumatic symptomatology, social impairment dimensions, and resilience. A hierarchical multiple regression analysis was performed to check for the effects of dose of exposure and specific type of interpersonal trauma on post-traumatic symptomatology. Results showed that traumatic experiences affecting interpersonal relationships (family torture, serious deprivation, and bereavement) predict higher levels of PTSD, while the protective role of resilience on PTSD outcomes turned out to be inhibited. The paper also discusses the implications for stakeholders and policy makers and defines the theoretical future developments of the research.