© 2021Bullying is widely recognized as a major psychosocial problem with substantial negative consequences. The current study aimed to estimate the prevalence of traditional school bullying and cyberbullying and reciprocal associations between bullying involvement and mental health problems. The sample of the study consisted of 6202 middle and high school students (age 11-18, M= 14.4 ±1.9 years, 54% boy). Bullying involvement, self-harm behavior, anxiety, depression, and psychosocial difficulties were assessed by self-report questionnaire. The prevalence of traditional school bullying and cyberbullying victimization was 33% (95% CI 32.1-34.5%) and 17% (95% CI 16.3-18.2%), respectively. The prevalence of traditional school bullying and cyberbullying perpetration was 22.4% (95% CI 21.3-23.4%) and 10.4% (95% CI 9.7-11.3%), respectively. Bullying involvement –as a victim, perpetrator, or both- was associated with anxiety, depression, psychosocial difficulties, and self-harm behavior. Girls were more likely to be affected than boys in mental health outcomes. A significant association between bullying victimization and negative mental health outcomes were also observed. These findings provide evidence to intervention strategies need to target both traditional and cyberbullying involvement. Understanding the risk profile will help create useful and appropriate interventions, which will reduce the early effect of bullying on mental health and modify the clinical course.