Background: Road traffic accidents are a major health hazard in the world. Everyday thousands of people are killed and injured on our roads. Objective: Our study aimed to determine attitude and behaviour of road traffic accident among high school student in Riyadh. Methodology: school based cross sectional study sample size was 197 among high school students in Diriyah, Riyadh, Saudi Arabia. high school students of Diriyah province. Inclusion level was 29 and 30 year of high school students. Exclusion was female and staff. Sample Technique was systematic random. Data collection using pretested, preceded questioner and analysed using SPSS version 20. P-value of less than 0.05 was considered significant result. Results: 96.5% of participants showed a good level of knowledge toward traffic regulation. 83.25% of participants showed a good attitude. 53.8% of participants were fully aware of the traffic signs. 51.3% of participants had an accident before. 26.9% had driving license. Conclusion: The majority of our respondent showed good level of knowledge regarding of traffic regulation, the minority of participants has driving license, almost half of participants use mobile phone while driving, most of participants don't use seat belt. Keywords: Attitude, Behaviour, Accidents, Traffic.