The article reports on 50 children with hospital (operation) traumas presented many years later to the doctor or educational consultant because of disturbed behaviour basing on an anxiety neurosis combined with a symbiotic mother fixation. In these cases, there was a clear connection between the triggering traumatising event the the existing symptom pattern. Most of the children had been admitted during infancy once or several times to special wards without sufficient psychological care and with restricted visiting hours. Tonsillectomy and strabotomy, as well as equilibrating operations, have proved to the particularly traumatising, especially in infants. This is evident even after several years and shows up during psychodiagnostic examination. Children who have suffered an accident and are admitted to hospital in a state of shock, are particularly susceptible to the hospital separation trauma. Preventive and curative psychohygienic measures are described. The mother's presence in the hospital has always remained the most reliable protection, from the infant's aspect, in all danger situations, including hospitalisation.