Within the ISO/TC22/SC12/WG1 „Child Restraint Systems” an ad-hoc group was founded to develop a test standard for side impact protection for children in child seats. Within this task an international database of accidents with MAIS 2+ injured children has been established. This material, from 10 research institutes, compiling a total database of 139 side impacts of children from 0-12 years, has been analyzed. From this sample a selected database with 69 cases has been assembled, where cases with misuse, ejection and catastrophic intrusions have been excluded to focus on accidents with correct working restraint systems. A detailed description of the selected accidents is given.For children sitting in a CRS, severe to critical injuries were observed mostly for head and cervical-spine, whereas 2/3- point belted children showed a higher incidence of thorax and abdominal injuries. Injury causation was analyzed in cases with forward movement of the child and compared between struck-side and non-struck side. Severe head injuries are found in connection with door, intruding object/opponent and A/B pillar contact. First results indicate that young children (0-3 years) showed an increased injury risk, therefore the development of a lateral crash standard should have priority with regard to the corresponding ECE groups 0+1 (US: infant and toddler seats).