Road traffic-related mortality has traditionally been regarded as a problem primarily of industrialized countries. There is, however, growing evidence of a strong negative relationship between economic development and exposure-adjusted traffic-related death rates. Cross-sectional data on road traffic-related deaths in 1990 were obtained from 83 countries. The relationship between such mortality and a number of independent variables was examined at the individual country level by means of multiple regression techniques. These were also used to elucidate factors associated with variations in age, sex, and case-fatality patterns of road traffic mortality. Countries were grouped according to region and socioeconomic features, and the mortality data were summarized by these groups. The gross national product per capita was positively correlated with traffic-related mortality/100,000 population/year (P = 0.01), but negatively correlated with traffic deaths/1000 registered vehicles (P < 0.0001). Increasing population density was associated with a proportionately greater number of traffic-related deaths in the young and the elderly (P = 0.036). Increasing GNP per capita and increased proportional spending on health care were associated with decreasing case-fatality rates among traffic-accident victims (P = 0.02 and 0.017, respectively). Middle-income countries appear to have, on average, the largest road-traffic mortality burden. After adjusting for motor vehicle numbers, however, the poorest countries show the highest road traffic-related mortality rates. Many industrialized countries would appear to have introduced interventions that reduce the incidence of road traffic injury, and improve the survival of those injured. A major public health challenge is to utilize this experience to avoid the predicted increase in traffic-related mortality in less developed countries.