Head injury is recognised as a major public health problem that is a frequent cause of death and disability in young people and makes considerable demands on health services. Epidemiological data are required to initiate appropriate preventive measures and to plan necessary services. However, reliable statistics are difficult to extract from routinely collected data. International statistics for accidental deaths and road accident deaths do not identify head injuries, but they do indicate differences in accident rates between countries and over time. For example, road traffic accident (RTA) deaths are more than twice as frequent in France, Australia, and the USA as in the UK or the Netherlands, but in developed countries they are steadily decreasing each year.1 In developing countries accident rates are increasing as traffic increases, and they greatly exceed those of developed countries. Asked about the main health hazard of the next decade a Chinese professor of public health replied “the motorcycle”. Head injuries account for one quarter to one third of all accidental deaths, and for two thirds of trauma deaths in hospital. They are also the main cause of lifelong disability after trauma. While the codes of the International Classification of Diseases do allow some estimates of the frequency of head injuries from routine statistics on deaths and hospital discharges, the 10 codes that cover head injury are variably applied; moreover, multiple injuries and transfers after first admission make estimates inaccurate. Injury severity scores used for trauma in general have been shown to be very inaccurate when applied to head injuries. Although people who present to hospital but are not admitted are a major part of the head injury problem for hospitals, no routine statistics are published for accident and emergency departments. Data published from clinical series are mostly from neurosurgeons whose selection criteria for …