This abstract summarizes recent statistics on the prevalence and causes of traumatic brain injuries (TBI), the populations it affects, and the degree of disability it causes. Estimates are based on 1985-1987 data from the National Health Interview Survey, a household survey of the noninstitutionalized U.S. population. Analysis indicates: the overall incidence rate is 0.8 percent, with young males having the highest incidence rates of any group; an estimated 31 percent of TBI is caused by moving motor vehicles; half of TBI cases are severe enough to cause a disability; firearms are the most common cause of fatality due to TBI; and strategies to reduce TBI should concentrate on youth and younger adults. Three tables provide detailed data on: (1) annual number and incidence rate of TBI cases, by gender and age; (2) annual number and incidence rate of TBI cases, by class of accident and place of accident; and (3) types of injury causing greatest activity limitation. (DB)