A consecutive, unselected series of 1812 cases of head trauma in children less than 15 years of age and admitted hospital over a period of 8.5 years was studied. Data concerning the grade of energy involved, the ages of the victims, the types of pathologies caused and the clinical features noted were collected and statistically analysed. Babies and toddlers (0-3 years) were shown to sustain rather low-energy trauma and suffer more skull fractures, more subdural haematomas and more benign injuries. They lost consciousness less frequently and were less frequently in coma than the other children. By contrast, they had more frequent signs of lateralization, and early seizures were much more frequent in babies than in other children. Young children (3-9 years) had rather higher-energy accidents, frequently lost consciousness, were more frequently in coma and have more frequently had a free interval associated with the development of brain swelling. They did not suffer subdural effusion or contrecoup lesions. Schoolchildren (9-15 years) were statistically more or less like young adults: the clinical sequences of trauma were more severe than in the other children, mortality was a little bit higher, the risk of extradural haematoma was higher, and they rarely suffered subdural haematomas or contrecoup lesions. Traffic accidents, with higher energy involved, were more severe.