Introduction: In the child’s life happen different psycho-traumatic events which may change his behavior and psychic functioning, all the more so as the child is younger. The psychic vulnerability of the child is his inability to resist to the constraints of the environment, the inability to influence them. The mother-infant separation remains a psycho-traumatizing event, being especially intense in the infant of 5 months to 3 years old. The child develops an anxious attachment reaction described by Bowlby, of which evolution and severity depends on the child’s age at the moment of the separation and of its duration. Material and method: 47 children have been assessed between 5,10 and 17,8 years old, with Attachment Disorder, admitted into the Clinic of Pediatric Neurology and Psychiatry Tg.-Mures in 2015, being psychically and psychologically examined, applying different specific scales and question- naires: STAI-C, MASC, SCARED-R, CAT, family drawing. The clinical diagnosis has been established according to DSM IV-TR and ICD-10 criteria. Results: The mother-infant separation is a psycho-traumatizing event which changes the child’s behavior all the more so as the child is younger. Conclusions: Mother’s absence or the psychic diseases of the biological parent, early institutionalization, physical and affective neglect, physical abuse, poor social and economic conditions, temperamental traits of the child, constitute an etiopathogenic factor determining: cognitive and affective disorders, psycho-somatic symptoms, emotional and behavioral disorders, adjustment disorders, pronounced personality traits.