The purpose of this study was to investigate post-traumatic stress symptoms affecting the involvement in school bullying and cyberbullying of boys and girls according to the different bullying roles. The current study involved 5058 Italian students, aged 11–18, recruited from secondary schools, who anonymously self-reported about school and cyber bullying as victims and/or perpetrators, and about post-traumatic stress symptoms. Based on their responses, students were classified as ‘only-bullies’, ‘only-victims’, ‘bully/victims’, or ‘not involved’ in school and/or online. The results showed that symptoms of post-traumatic stress differ between boys and girls and according to their roles. For cyberbullying, the bully/victims and only victims reported higher post-traumatic stress symptoms. For school bullying, bully/victims and only bullies reported higher symptoms of stress, and girls overall have higher values of such symptoms. It was concluded that both school and cybe rbullying are risk factors for concurrent development of post-traumatic stress symptoms, differently affecting adolescents according to their role. The bully/victims both at school and online reported higher levels of post-traumatic stress, indicating that this is a high risk group that needs special attention and that school bullies, and only victims develop stress out of their behaviour and need to be targeted for prevention of worst health consequences, especially focusing on girls.