Using a 1977 sample of emergency department visits in five northeastern Ohio counties, population-based injury rates are tabulated by age, sex, and cause. Case fatality ratios are estimated by comparing these injury rates with population-based mortality rates for 1976-1978. For all age and sex groups, injuries are a major cause of emergency department visits. Falls, striking, cuts, and motor vehicle crashes are the leading causes of injury. Case fatality ratios for motor vehicle crash injuries are considerably higher than those for non-transport injuries. Injury rates and case fatality ratios for males exceed those for females except among the elderly. With increasing age, injury rates decline but the fraction of injuries leading to hospital admission or to fatality rises sharply.