Background: School bullying is serious health problem that affect school children in Egypt and all over the world, so assess children, parents and teacher knowledge and practice to face this problem which may be in the face of them every day of school days is very important. Aim: Assessment of bullying behaviour among school age children. Design: Descriptive exploratory design. Settings: The study was conducted at two primary schools named Al Farouk Omar primary school and Alhai Alawal primary school affiliated to 6^th of October Educational Administration. Subject: A purposive sample composed of (n=600) primary school children from the 4th to 6th grades and their parents, convenience sample of teachers (n=150). Tools: three tools were used for data collection; First tool: Peer interaction questionnaire that include two parts; characteristics of children and assessment of children history of bullying; Second tool: Interviewing structured questionnaire format related to teachers containing three parts: Teachers characteristics, assessment of teachers' knowledge and assessment of teachers' intervention toward bullying; Third tool: Interviewing structured questionnaire format related to parents containing three parts:Parents characteristics, assessment of parents knowledge and assessment of parents response to bullying. Results: The current study revealed that about 97% of studied children were involvement in bullying behavior as victim or bully with different categories of involvment, 35.3% of studied teacher had unsatisfactory knowledge and 47.3% of them less involvement in bullying intervention,and 30.7% of studied parents had poor knowledge about bullying and 29.8% had negative response to it Conclusion: the majority of school children were involvevement in bullying behavior(victim/bully), more than one third of studied teacher had unsatisfactory knowledge and about half of them less involvement in bullying intervention and about one thired of studied parents had poor knowledge and negative response toward bullying behavior.Recommendation: Encourage of integrated programe for all the concerned: children, parents, teachers, school staff and administrators.