A consecutive unselected series of 1812 children (up to 15 years old) admitted for head injuries over a period of 8.5 years was studied. The cases were divided up according to five categories of pathology: benign injury, extradural haematoma, subdural haematoma, open brain laceration and brain contusion in a broad sense. All cases of benign injury were from the Geneva area (57000 children) and 52% of the cases of severe injury were referred from other places. To these 1812 cases were added those of 23 children who died before admission recorded by the police. In the Geneva area the mortality was 6.8/100000 per year. Patients were divided into three age groups: I (0-3 years), II (3-9 years), and III (9-15 years); group I was further subdivided into subgroups Ia (0-1 year) and Ib (1-3 years). The incidence of each type of accident was calculated for each age group, separately for girls and boys. Each type of pathology was correlated, sex by sex and for different ages, with the type of accident. Overall, two boys were injured for each girl. Road accidents were responsible for 15% of head injuries in group I girls, 17% in group I boys, 43% in group II girls, 45% in group II boys, 50% in group III boys and 61% in group III girls. They were responsible for 94% of all deaths and 85% of deaths of hospitalized patients. Falling was the most frequent cause of injury. Benign injuries were more frequent in group I. Only 1 of 25 patients with extradural haematomas died, and there were only 8 patients with subdural haematomas, 4 in subgroup Ia (babies aged less than 1 year).