肥胖是導致許多慢性病的危險因子，影響健康甚鉅。為瞭解肥胖在青少年中盛行的情形，並比較各類體型指數用來篩選肥胖的結果，以臺北市立國民中學八十學年度全體新生共47,173名樣本中，進行系統集束抽樣調查。1174名樣本中，有1168人填答問卷，同時接受身高、體重、和皮脂厚度測量。結果發現，採用「皮脂厚度的第八十五百分位值」、「體質指數的第八十五百分位值」、及「超出平均體重20％」等三個肥胖標準，篩選出來的肥胖盛行率，在男生方面為15.0-17.3％；在女生方面則介於14.8％至15.6％之間。各類體型指標之間的相關值達到0.66至0.98之間；同時篩選出肥胖者的一致率達89.3％至93.5％之間。青少年的體型常模宜建立並定期更新；各國民中學可就各校學生的身高和體重資料，按分佈情形篩選肥胖生，以便及早實施體重控制教學計畫。

　　　　　Obesity poses a significant risk factor of chronic disease for individual's health. In order to understand the prevalence of obesity in adolescents, and compare the results using vaious methods for estimating body composition, a cross-sectional survey was conducted in 1991. A systematic sampling procedure by cluster was employed. 1168 subjects were selected form Taipei City Junior High Schools which included 47,173 seventh graders. The subjects were asked to complete a set of questionnaires. A measuremetn of height, weight, asd skinfolds was also administered. When a skinfold exceeding the 85he percentile, a BMI exceeding the 85th percentile, and a weight more than 20% of average weight were adopted as criteria, the prevalence rates of obesity were 15.0-17.3% for males and 14.8-15.6% for females. The correlation coefficients of 0.66 to 0.98 between indices were found. The concordance rates for screening obesity by different indices were 89.3% to 93.5%. It is expected to establish were 89.3% to 93.5%. It is expected to establish adolescent body composition norms periodically. A distribution of body composition index can be developed using the height and weight data of students in each school. Based on the distribution, the obeses will be selected. It suggests to provide a weight control program in school as soon as possible.