The main purpose of this study was to evaluate the prevalence of overweight and obesity among guidance-and high school students and its relation to modifiable environmental factors."nMaterials and Methods: The subjects have been 1000 girls and 1000 boys aged between 11-18 years, selected by multi-stage random sampling, their parents (2000 subjects) and their school staffs (500 subjects) in urban and rural areas of two provinces in Iran. Data have been analyzed by SPSSV10/ Win software."nResults: The prevalence of 85th < BMI95th percentile in girls was significantly higher than boys (10.67±1.1%, 2.9±0.1% VS. 7.37±0.9%, 1.87±0.1% respectively, p 85th percentile was more prevalent in those with lower educated mothers (9.2+2.1 vs. 11.5+2.4 years of mothers education respectively). The mean of the total energy intake was not different between overweight or obese and normal- weight subjects (1825±90Kcal VS. 1815±85Kcal, P>0.05) but the percent of energy derived from carbohydrates was significantly higher in former than the latter (69.4% VS. 63.2%, P