This study was conducted on 585 children, 3 to 5 years of age, at five preschools in inner and suburban Hanoi, 287 children in the inner city and 298 children in the suburban area. Anthropometric methods, sociological methods and WHO standards were used to evaluate the children's overweight/obesity status and investigate factors related to the overweight-obesity status of the children. It was found that 13.85 percent of the children were overweight and 5.98 percent were obese. The percentage of overweight-obese children in inner Hanoi was greater than that in suburban Hanoi. Factors related to the overweight-obesity status of children included nutrition, physical activity, and family economic status.