OBJECTIVE: To determine if there is evidence of obesity in low-income Hmong children. DESIGN: Cross-sectional survey. SETTING: Women, Infants, and Children clinics in Minneapolis, Minn. PARTICIPANTS: 271 US-born Hmong children, ages 1.00 through 4.99 years. SELECTION PROCEDURES: Consecutive sample of all Hmong children seen in two clinics between September and December 1989. INTERVENTIONS: None. MEASUREMENTS/MAIN RESULTS: Heights and weights were measured and converted to National Center for Health Statistics z scores of weight for age, height for age, and weight for height. Relative to National Center for Health Statistics reference data, mean height-for-age z scores decline progressively after age 2 years to--1.2 z at age 4.5 years. Mean weight-for-height z scores exceeded the National Center for Health Statistics reference significantly at ages 3 and 4 years, and there was more than a fourfold excess of Hmong children beyond the 95th percentile in weight for height at these ages. CONCLUSIONS: There is evidence of early obesity in Hmong children, an ethnic group heretofore considered to be a low risk for obesity.