A cohort of hypercholesterolemic (HC) 4-10 year old children (n=227, mean total cholesterol (TC)=197.0±14.1 mg/dl) and an age and gender matched group of non-hypercholesterolemic (NHC) children (n=80, TC=140.0±20.0 mg/dl) were identified. The HC and NHC groups had similar mean ages(6.4±1.8 vs. 6.3±1.7 years), heights (118.9±0.4 vs. 120.0±0.6 cm), and weights (23.6±0.3 vs. 23.6±0.4 kg), both contained 51% girls, and were all Caucasian. Weight-for-height percentile, midarm circumference, and skinfold measures were all larger for the HC group. The differences in the skinfold thickness measures were more pronounced for the truncal measures (subscapular and suprailiac) and were expressed in the 8.0-9.9 year old children, but not the 4.0-5.9 year olds. For the subgroup of HC children for whom insulin levels were available (n=185), insulin levels were associated with measures of obesity in an age-related manner, but not with cholesterol levels. These results suggest that an age threshold exists for the expression of the altered body composition of hypercholesterolemic children and that altered insulin levels are expressed with this altered body composition.