Of interest is how some countries have achieved a profound reduction of child injury mortality. Still little is reported on the impact of a combination of urban planning, social welfare development and safety measures. We therefore present trends in childhood (0-14 years) injury mortality in Sweden 1966-2001 and discuss the factors behind any reductions observed. Annual total and cause-specific injury mortality rates were computed by age subgroups and gender. Trend analyses were performed with year as independent and mortality rate as dependent variable. A piecewise linear function was fitted to the annual mortality rates. Data were categorized into five 7-year intervals. In total, there were 5264 deaths due to injury in the study population during the period 1966-2001, of which 3368 (64%) were of boys and 1896 (36%) girls. The most frequent external cause of death was transport injury (48%), drowning (14%), homicide (5.8%), fire (5%), and fall (2.7%). About 66% (n=3474) of deaths occurred during the first half of the study period (1966-1981) with an average incidence rate of mortality 13.0 compared to 5.6 per 100,000 inhabitants during the second half of the period (1982-2001). For total injuries, there was a statistically significant decrease in mortality among all subgroups of children in both sexes. The slopes are greater among the younger children (0-4, 5-9 years) than the older ones (10-14 years). Several factors behind this strong decline of childhood injury mortality of interest to evaluate are (i) the implementation of the functionalist architectural style including transport separation, legislation and safety in cars; (ii) the expansion of public child day-care centers including more organized leisure activities; (iii) the establishment of long-term nationwide mandatory program for swim training among school children and (iv) local child-safety programs considering differences in exposure to risk between urban and rural areas.