Background: Childhood obesity is a major public health issue in developed countries, and frequently proceeds into adulthood. The aim of this study was to estimate the prevalence of obesity and abdominal fat distribution in 6-12 years old children from the central region of Portugal, providing new data about trends on prevalence, epidemiology and evolution in obesity. Methods: Weight, height and waist circumference were measured in a random representative sample of 1,433 children (747 girls and 686 boys) from public schools in 2011. International Obesity Task Force (IOTF) cut-offs were used to define overweight and obesity. Abdominal obesity was estimated using the sex and age-specific ≥ 90th waist circumference percentile and waist-to-height ratio cut-off. Results: The prevalence of overweight and obesity among children was 33.0%; 10.7% were obese. Overweight was significantly higher in boys than in girls (p = 0.044), whereas no gender differences was found in obesity (10.6 % in boys and 10.7% in girls, p = 0.571). The prevalence of abdominal obesity based on waist circumference was similar in girls and boys (3.8% vs. 3.9% respectively; p = 0.924), but significantly higher in boys than in girls based on waist-to-height ratio (28.1% vs. 19.4%, respectively; p = 0.009). Comparison with previous studies showed a slightly increase in overweight/obesity in children of central Portugal in the last 10 years, reaching values of 40.0% prevalence in the 7-9 years old. Conclusion: In conclusion, this study shows a very high prevalence of overweight/obesity and abdominal obesity among Portuguese children, following the trend of other southern European countries. Thus, it is of the utmost importance the development of preventive and treatment strategies.