Childhood obesity is an established problem in many countries and emerging in others. Epidemiological data on obesity in children is essential in order to plan public health policy and services. A study was conducted to determine the prevalence of obesity in schoolchildren in the fifth grade of elementary school (10-12 years old) in the district of Kuala Selangor. Ten schools of which five are in urban and five in rural areas were selected consisting of 699 eleven year old schoolchildren from the three major ethnic groups. Using international cut-off points for obesity, we report an overall prevalence of obesity of 7.2%. Prevalence of obesity in urban children is 7.2% whereas in rural children it is 7.0 %. Analysed by gender, there were 8.9% obese boys and 5.3% obese girls. Among the 3 major ethnic groups, the Malays had the highest prevalence of obesity at 9.3% followed by the Chinese with 6.6% while among Indians 3.0%. The data obtained from this study suggests that obesity in Kuala Selangor children is a cause for concern in urban and rural areas.