Objective: Traditional peer bullying (TPB) is a worldwide problem and 20-56% of adolescents are thought to be affected. Some studies suggest that internet addiction may be related to negative behaviors such as bullying. This study aimed to determine the prevalence of TPB in the clinical psychiatric sample of adolescents and to investigate the predictive effect of age, gender, psychiatric diseases and (internet addiction) IA on roles in TPB. Methods: This cross-sectional study conducted with 214 adolescents in the age range of 12-16 years. Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version were used for psychiatric evaluations of the participants. Olweus Bully/Victim Questionnaire (OBVQ) and Young Internet Addiction Scale were carried out to all participants. The predictive effect of age, gender, IA and psychiatric disorders on roles in TPB was evaluated by multinomial logistic regression analysis. Results: The mean age of the participants was 14.5 years. According to the results of the OBVQ, 49% of the participants were involved in TPB (victims: 35%, bullies: 14%). Regression analysis revealed that age and gender had no effect on roles in TPB, but IA had a predictive effect on both victimization (p<0.001) and bullying (p<0.001). It was found that depressive disorder had a predictive role in victims (p<0.05) and disruptive behavior disorders (DBD) had a predictive role in bullies (p<0.05). Discussion: Peer bullying was a serious problem (one of two adolescents) in psychiatric clinical population of adolescents and IA positively predicted being a victim and a bully. When peer bullying was evaluated by roles, it was observed that psychiatric problems related to these roles were different. Depressive disorder has predictive effect in victims and disruptive behavior disorder in bullies. The findings of this study may be useful in the development of prevention and intervention programs for adolescents affected by TPB.