Objectives: To report prevalences of overweight and obesity in a large sample of American Indian children from a survey in 2002-2003, and to evaluate the cha nge in prevalences since 1995-1996 when children on the same reservations were measured. Design: Analysis of survey data. Setting: Aberdeen Area Indian Health Service (North Dakota, South Dakota, Iowa, and Nebraska). Participants: A total of 11 538 American Indian children (aged 5-17 years) attending 55 schools on 12 reservations. Main Outcome Measure: Height and weight measured during the 2002 -2003 school year by the same team as in the earlier survey. Prevalences of overweight (≥85th percentile)-and obesity (≥95th percentile) were calculated on the basis of body mass index (calculated as weight in kilograms divided by the s quare of height in meters) and the Centers for Disease Control and Prevention gr owth charts. Results: At 5 years of age, 47%of boys and 41%of girls were overw eight, and 24%of the children were obese. Prevalences of overweight and obesity exceeded those for the most recent available data for all US children at almost every age. In the intervening 7 to 8 years between surveys, prevalences of over weight and obesity continued to increase in the children by 4.5%and 4.3%, resp ectively. Conclusions: Prevalences of overweight and obesity in the most recent sample of American Indian children indicate that they are at even higher risk fo r these conditions and their healthrelated sequelae than the best estimates for all US children, with prevalences as high as or higher than those for any other racial or ethnic groups of children reported in the most recent national surveys . Objectives: To report prevalences of overweight and obesity in a large sample of American Indian children from a survey in 2002-2003, and to evaluate the change in prevalences 1995-1996 when children on the same reservations were measured. Design: Analysis of Participation: A total of 11 538 American Indian children (aged 5-17 years) attending 55 schools on 12 reservations. Main Outcome Measure : Height and weight measured during the 2002-2003 school year by the same team as in the earlier survey. Prevalences of overweight (≥85th percentile) -and obesity (≥95th percentile) were calculated on the basis of body mass index (calculated as Weight in kilograms divided by the quare of height in meters) and the Centers for Disease Control and Prevention gr owth charts. Results: At 5 years of age, 47% of boys and 41% of girls were overw eight, and 24% of the children were obese. P revalences of overweight and obesity exceeded those for the most recent available data for all US children at almost every age. In the intervening 7 to 8 years between surveys, prevalences of over weight and obesity continued to increase in the children by 4.5% and 4.3% , respctively. Conclusions: Prevalences of overweight and obesity in the most recent sample of American Indian children indicate that they are at even higher risk fo r these conditions and their healthrelated sequelae than the best estimates for all US children, with prevalences as high as or higher than those for any other racial or ethnic groups of children reported in the most recent national surveys.