Background: Bullying is a major problem in every aspect of life span is one of the biggest challenging areas within the field of education. Bullying perpetration and bullying victimization have been observed worldwide among adolescents and being victimized is associated with poor mental health. Aim: The current study aimed to assess bullying and its effect on mental health among secondary school students. Research design: This study used descriptive correlational design. Setting: This study was conducted at the secondary schools selected in Benha City. Sample: Multi stage random sample of 300 students. Tools of data collection: Data were collected usingSocio-demographic Questionnaire, Olweus Bully and victim Questionnaire, Mental Health Inventory. Results: The common factors influenced bullying and were significantly associated with the occurrence of bullying in Benha secondary school such as: age 15 Conclusion: Almost of the studied subjects were victims. There was significance positive correlation between victim and mental health. Recommendations: The current study recommended that psychiatric mental health nurse, school health nurse and social workers provide psycho-educational program in schools to equip students social and interpersonal skills and know them the negative effect of bullying on colleagues.