OBJECTIVE: To investigate the incidence of simple obesity and risk factors for the development of this disorder in preschool children from Urumqi City. METHODS: A total of 1 730 children at ages of 3-7 years sampled randomly from four district kindergartens of Urumqi City were enrolled in this study. Their heights and weights were measured. Risk factors for the development of simple obesity were investigated by multivariate logistic regression analysis. RESULTS: Overweight occurred in 229 children (13.2%). One hundred and twenty-two children were diagnosed with simple obesity (7.1%). The 5 years old group children showed the highest incidence of obesity (9.5%), more than the other age group children. Multivariate logistic regression analysis showed that family history of obesity, high body mass index of the mother, little physical activity of the father, and bad diet habits and low educational levels of parents were risk factors for the development of simple obesity. CONCLUSIONS: The incidence of simple obesity of preschool children from Urumqi City is higher than the reported data. The risk of childhood simple obesity is multifactorial. The prevention of simple obesity should begin at the preschool stage.