A total of 1152 patients under 20 yr of age with 1611 accidentally traumatized teeth treated at the Helsinki Health Center oral surgery clinic in 1979 and 1980 were studied with respect to the etiology, type, extent and severity of their injuries. The mean age of the patients was 11 yr and the male: female ratio was 2.7:1. The prevalence was highest in the age group 7‐10 yr for girls and in the age group 11–15 yr for boys. More injuries were recorded as having taken place outside school or kindergarten and in the fall and winter months. Most of the injuries were exclusively hard tissue traumas; 81% were estimated as mild, 15% as moderate, and only 4% as serious and needing specialized treatment. Typical causes were accidents at school (28%) or at home (27%), while only 11% were traffic accidents, 21% were due to sports and 11 % due to acts of violence. These last three etiologies were more common among the boys (p< 0.001). Violence was the main etiology for tooth injuries among patients aged 16–20 yr (p<0.001), resembling the findings regarding causes of facial bone injuries. The proportion of home or school accidents seemed to be decreasing in relation to traffic and sports accidents, which were more numerous in 1980 than in 1979. Most accidents were single‐tooth injuries, but the youngest and oldest age groups involved more cases of 3 or more simultaneous tooth traumas than did the other age groups.