Background: Traumatic brain injuiy (TBI) is in the developed countries the most common cause of death and disability in childhood. Aim: The purpose of this study is to estimate the incidence of TBI for children and young people in an urbanised region of the Netherlands and to describe relevant characteristics of this group. Methods: Patients, aged 1 month - 24 years who presented with traumatic brain injury at the Erasmus University Hospital (including the Sophia Children's Hospital) in 2007 and 2008 were included in a retrospective study. Data were collected by means of diagnosis codes and search terms for TBI in patient records. The incidence of TBI in the different referral areas of the hospital for standard, specialised and intensive patient care was estimated. Results: 472 patients met the inclusion criteria. The severity of the Injury was classified as mild in 342 patients, moderate in 50 patients and severe in 80 patients. The total incidence of traumatic brain injury in the referral area of the Erasmus University Hospital was estimated at 113.9 young people per 100.000. The incidence for mild traumatic brain injury was estimated at 104.4 young people, for moderate 6.1 and for severe 3.4 young people per 100.000. Conclusion: The ratio for mild, moderate and severe traumatic brain injury in children and young people was 33.7-1.8-1.In the mild TBI group almost 17% of the patients reported sequelae. The finding that 42% of them had a normal brain CT scan at admission underwrites the necessity of careful follow up of children and young people with mild TBI. (C) 2011 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.