To evaluate the psychometric properties of the Impact of Event Scale (IES scale) in children a study was conducted on 1787 children exposed to the warfare in Croatia, Bosnia and Herzegovina. The study group comprised 877 girls and 910 boys ranging in age from 6 to 15 years attending 28 arbitrary selected schools in Zagreb. High levels of posttraumatic reactions were found in the group of children. The pattern of endorsement and the factor structure of the IES scale were similar to that found in other samples. This supports the use of the IES in the assessment of posttraumatic stress reactions in children. Two factors emerged from a Principal Component Analysis, labeled intrusion (9 items), and avoidance (4 items). As in other studies, this study documented problems with several items (items 2, 12 and 15), items that should be considered omitted from the IES. Girls reported significantly more distress on 13 out of the 15 items. Both the overall IES score as well as the intrusion and avoidance score were significantly higher in girls than boys. The factor structure for boys and girls were very similar, and the reliability of the scale was adequate across different age groups and for subgroups of displaced and refugee children.