STUDY OBJECTIVE: To measure socioeconomic differences in injuries among different age groups of children and adolescents. SUBJECTS: Children under 20 living in Sweden between 1990 and 1994 (about 2.6 million). METHOD: A cross sectional study based on record linkage between 15 Swedish national registers. Children were divided into four age groups and allocated to four household socioeconomic status groups. Absolute and relative risks were compiled using children of high/intermediate level salaried employees as the comparison group. Four diagnostic groups were considered: fall, traffic, interpersonal violence, and self inflicted injuries. RESULTS: Injury incidences were relatively low and socioeconomic differences negligible in the 0-4 year olds. Thereafter, significant socioeconomic differences were observed in all diagnostic groups except falls. The highest absolute differences were in traffic injuries, especially among 15-19 year olds, and in self inflicted injuries among 15-19 year old girls. Relative differences were highest in both categories of intentional injuries for the age group 10-14. Social circumstances in the household other than family socioeconomic status affected the social pattern of intentional but not that of unintentional injuries. CONCLUSIONS: Socioeconomic differences in injury risks are not necessarily constant over age. Inequalities are particularly high in absolute terms among adolescents 15-19 years old for traffic injuries and in relative terms among 10-14 year olds for intentional injuries.