From 1990 through 1992 we conducted surveillance of cases requiring hospital admission and of fatal cases of traumatic brain injury among residents of Utah and found an annual incidence rate of 108.8 per 100,000 population. The greatest number of injuries occurred among men and persons aged 15 to 24 years. Motor vehicles were the leading cause of injury, followed by falls and assaults. The incidence rate we found is substantially lower than previously published rates of traumatic brain injury. This may be the result of a decrease in the incidence of these injuries in the decade since earlier studies were done, as well as changing hospital admission criteria that serve to exclude less severe cases of injury. Despite the apparent decline in rates, our findings indicate the continued importance of traumatic brain injury as a public health problem and the need to develop more effective prevention strategies that will address the major causes of these injuries.