Obesity is a multifactorial consequence that in addition to genetic and metabolic effects, changes in lifestyle habits such as inappropriate diet and reduced physical activity and sedentary are the main causes of obesity, so this study was conducted to identify lifestyle status in elementary school children in Tehran. In this cross- sectional study, 156 obese pupils (BMI≥ 95 th percentile) with 7 year-old were selected randomly from ten health centers in five districts of Tehran. Weight, height, body mass index, waist and hip circumference were measured. For each subject a questionnaire on demographic characteristics and physical activity were completed by interviewing their mothers. Data were analyzed using SPSS. Mean age, birth weight and height of children, were respectively 80±3.8 (month), 3.3± 0.6 (Kg) and 50.14± 3.1 (Cm). Evaluating anthropometric indices, showed that the mean weight, height, waist and hip circumference, and BMI in children were 37.3± 6.2(Kg), 1.3± 4.8(Cm), 78.8± 5.6(Cm) and 73.9± 6.1(Cm) and 23.0±2.8(Kg/ m2) respectively. 85% family size, belonging to 4≥ households. The highest level of education was higher than diploma, 55% and 50% in fathers and mothers respectively. 72% of mothers were housewives. 81% of obese children, had a behavior of sedentary and only 38% of them had special physical activity weekly. 67% of them use to eat while watching TV and playing computer game. Only 15% of them had gone to school by walking. Considering the increasing of obesity and non-communicable diseases are the threat for the health of next generations, not only affect the current situation of children, but also in the future the development of community will be challenged. Therefore, implementing appropriate intervention programs with emphasis to reduce sedentary, is highly recommended.