The prevalence of overweight and obesity among children appears tobe rising rapidly in Taiwan and many other countries around the world. Weexamined the anthropometric status of elementary schoolchildren in Lanyuand compared the prevalence of overweight and obesity with school-agedyouths according to data from Nutrition and Health Survey in Taiwan, 1993-1996 (NAHSIT). Total 255 schoolchildren (138 boys; 117 girls) aged 7 to 12years living in Lanyu, an off shore island in Taiwan; were selected for thiscross-sectional study. Height and weight were measured and BMI calculated.Overweight, obesity and underweight were based on the recommendationby Department of Health Executive Yuan Taiwan, using age-and genderspecificBMI values set by Chen et al. The overall prevalence of overweight,obesity and underweight were 10.6%, 7.1% and 12.9% respectively. Also theprevalence of overweight, obesity and underweight among girls were 16.2%,5.1% and 12.8%; among boys were 5.8%, 8.7% and 13.0% respectively.This study provides valuable information on the current anthropometricmeasurements of Lanyu elementary schoolchildren. New longitudinal studiesare needed to estimate the trends of body fat status in Lanyu.(Taiwan J Fam Med 2007; 17: 109-16) 近年來全世界學童過重和肥胖的盛行率持續上升，台灣也不例外。本研究主要是調查蘭嶼小學學童身高、體重的體位情形及以身體質量指數（BMI）來評估過輕、過重、肥胖學童比例，並且和台灣國民營養健康調查1993-1996結果作比較。我們以行政院衛生署2001年公佈的兒童身體質量指數數據為標準值，定義BMI≤15百分位為體重過輕、85百分位≤BMI<95百分位體重過重、BMI≥95百分位為肥胖。結果顯示255位蘭嶼小學學童（男138；女117）中，10.6%為體重過重，7.1%為肥胖，而體重過輕則為12.9%。以性別區分，蘭嶼女學童16.2%為體重過重、5.1%為肥胖、12.8%為體重過輕；男學童體重過重佔5.8%、肥胖8.7%、體重過輕13.0%。（台灣家醫誌2007; 17: 109-16）