The present study was aimed at analysing body composition in children aged 13 who, while showing normal BMI, had waist circumference above the 90th percentile, indicative of visceral fat accumulation. The study showed the situation to be related both to the elevated percentage of adipose tissue in the body and to reduced percentages of fat-free body mass and water. The girls examined showed their body fat percentage to vary within 19.5-32.7% (mean 26.9±3.8%) against the reference level of 18-25%; the girls’ fat-free body mass ranged within 67.3-80.5% (mean 71.3±3.8%) against the reference level of 72-82%; the percentage of water in their body ranged within 50.9-60.8% (mean 55.3±2.9%) against the reference level of 57-62%. The boys examined showed their body fat percentage to vary within 20.5-35.5% (mean 25.3±6.4%) against the reference level of 12-18%; their fat-free body mass to range within 64.7-89.5% (mean 74.7±6.4%) against the reference level of 82-88%; and the percentage of water in their body to vary within 48.3-66.9% (mean 55.8±4.8%) against the reference level of 61-66%. As shown by the results, the normal BMI cannot be the only criterion with which to assess the nutritional status of a child, particularly at puberty.