The epidemiology of head injury was studied in the Bronx, N.Y., for the period March 1980 through February 1981. Using a ratio estimation sampling scheme the annual incidence rate, age-adjusted to the 1980 US population was estimated to be 249/100,000. Rates for males were more than twice those for females. Incidences were highest for blacks and Hispanics; this was primarily attributable to high rates of injuries caused by violence in young adult males. Violence and falls were the most frequent causes of injuries, and only 27% of all head injuries were associated with traffic accidents. The annual age-adjusted mortality rate was 27.9/100,000. Over half the mortality was associated with head injuries due to violence.