Background: Increased time spent on sedentary activities and decreased time spent on physical activities has been linked with lower levels of energy expenditure, overweight, obesity, and increased risk of cardiovascular and metabolic diseases. During the past few years, rapid improvements in living standards, mechanization and urbanization has a profound impact in the Kingdom of Saudi Arabia resulting in low levels of physical activity and sedentary living. Therefore the purpose of the research is to provide basic data of subjectively measured physical activity and sedentary behavior of the Saudi school children in relation with BMI.