Childhood obesity increases the risk of morbidity whether or not obesity persists into adulthood. Measurement of body fat content using bioimpedance analysis (BIA) is a useful tool in epidemiologic studies. Both tricep skinfold thickness (TST, mm) and body mass index (BMI, kg/m(2)) are indirect, simple methods and easy to perform for assessing body composition. These methods are generally accepted as good clinical measures for defining childhood obesity. The aim of our study was to evaluate fat mass (FM, kg and %) measurements using TST and BIA (50 kHz) in a cohort of 6-year-old Italian children. A total of 228 southern Italian children (121 boys, 107 girls), randomly selected in nine local primary schools, were included in the study. The correlation between methods for measuring FM was calculated. Linear regression analysis showed a significant positive correlation between FM measured with BIA and BMI ( r=0.92, p<0.001) and with TST ( r=0.79, p<0.001). We conclude that FM measurement using TST and BIA is comparable in different BMI ranges. However, BIA is a useful and alternative method for detecting body composition in children and may be a more precise tool than TST for measuring FM in epidemiological studies in pediatric populations.