Objective: The aim of this study was to determine the frequency of injuries and related factors among first grade students of three high schools in different socioeconomic regions of Ankara. Material and Methods: The target population of this cross-sectional study consisted of the first grade students of three high schools. The aim was to reach all the first grade students of the two schools, which were in the high and low socioeconomic regions, whereas a sample of students was selected from the school in the region of medium socioeconomic level, since the number of students of that school was very high. The study questionnaires, which included questions related to socio-demographic features as well as life style and frequency of injuries, were completed by the students under observation. In the study, logistic regression model was used to analyze the risk factors for injuries in the last three months. Results: In the study, 401 students (60.4% male and 82.3% between 15-16 years of age) were enrolled. The frequency of injuries among the high schools in the last three months varied between 33.3-46.8%; the difference between schools was statistically insignificant. After controlling for the school variable, injury risk was 1.80-fold [95% confidence interval (CI) 1.07-3.05] higher for males, 2.27-fold (95% CI 1.23-4.17) higher for students carrying guns and 2.8-fold (95% CI 1.64-4.78) higher for students who were exposed to violence. School absenteeism of students with any kind of injury ranged from 0 to 30 days according to their type of injury. Conclusion: Injuries are common among adolescents and are important causes of student absenteeism. This finding indicates the need for interventions on both prevention and first aid. Adolescents should be informed that injuries are preventable and new approaches are needed for them to adopt safe behaviors. Moreover, social and psychological support should be available for adolescents who are under risk to adopt safe behaviors.