The number of very young children exposed to trauma is under-represented. Trauma interferes with the organisation and development of brain structures and thus may have lasting effects on the individual's life. Traumatic stress disorder (TSD), which is the Axis I diagnosis used in the under-three patient population, encompasses four symptom clusters. Of note is the integral part of the Relationship Disorder Classification (Axis II) during this phase of life. The capacities needed to experience and recall early trauma are largely present from the beginning of life and rapidly develop during the first six months. The treatment of traumatic stress disorder rests on establishing a sense of safety, reducing the overwhelming affects evoked, helping the child to form a coherent narrative and thereby aiding the integration and psychological mastery of the traumatic event. The support of the attachment relationship with an adequate caregiver is pivotal.