The objective of this study was to assess the prevalence of overweight and obesity in 10-7 year -old schoolchildren in two schools, and examine the association of factors such as gender, age and type of school. This is a cross-sectional, prospective study with a total of 80 male and female students between 7 and 10 years of age; 40 of whom were enrolled in a municipal public school and 40, in a private school in the city of Barra do Garcas, MT. A body mass index (BMI) was calculated on all students using the 2007 World Health Organization curve. It was observed that adequate BMI and obesity were higher in the public school, although greater overweight rates were found in the private school, with high results among male students. All in all, overweight and obesity were observed in 52.5% of cases in public schools and 60% in private schools, with an increasing trend among male students in private schools. These data support the importance of implementing health education programs through Physical Education classes as a disease prevention strategy.