Cross-sectional studies have produced clear inverted U-shaped curves between injury mortality and economic development; yet, this does not mean that single countries will necessarily follow similar curves as they grow richer over time. This study was conducted to examine whether previous cross-sectional findings can be verified using a longitudinal approach. Data for both injury mortality and gross domestic product (GDP) per capita were obtained from an official health database for the member countries of the Organization for Economic Cooperation and Development (OECD) for the period of 1960-1999. Regression models were then used to examine the longitudinal relationship between these two variables. Substantial improvements in injury mortality were observed in all income categories in the selected countries. For higher and middle high-income countries, injury mortality rates (all causes) increased until 1972, peaking in 1972 and then declining. For industrialized countries with relatively low GDP, injury mortality rates increased until 1977 and then declined. Using cubic regression lines for injury mortality rates, for all income categories, injury mortality rates increased up to a GDP per capita of USD 3,000-USD 4,000, then decreased significantly. The rising trends of suicide and homicide rates were observed until countries attained a GDP per capita of around USD 13,000-USD 14,000 for all income categories. It is noteworthy that compared to the intentional injury categories, mortality due to road traffic accidents and injuries from falls declined earlier on in the economic development process. Longitudinal analysis among high-income countries confirms earlier cross-sectional findings; that is, most injury categories seem to follow inverted U-shaped trend lines, with declining trends after peaking at various stages of temporal and economical development. A comparison between time and economy suggests that differences in peaking time between countries for the same injury category is partly a reflection of temporal differences in economic development.