Children in China are experiencing a rapid increase in the prevalence of obesity, which is associated with hypertension. To compare the effect of body fat on blood pressure (BP) with that of the normal physical growth, we compared BP levels in Chinese children with different body fat levels. In the present population-based study, 13 972 children in the highest-skinfold-thickness-quartile group were individually matched to 13 972 children in the lowest-skinfold-thickness-quartile group by height and weight. Similarly, 5103 children in the highest-waist-circumference-quartile group were matched to the same number of children in the lowest-waist-circumference-quartile group. The high- and low-fat groups had similar height and weight but the high-fat group had significantly higher skinfold and waist circumference measurements. The differences in systolic BP (SBP) between the high- and low-skinfold-thickness groups were small: 0·01 (95 % CI -0·41, 0·44) mmHg in boys and 0·20 (95 % CI -0·15, 0·54) mmHg in girls. The differences in diastolic BP (DBP) were also small (0·39 and 0·38 mmHg for boys and girls, respectively) but were statistically significant. The differences in both SBP and DBP between the high- and low-waist-circumference groups were small but not statistically significant. For a given body size as measured by height and weight, relative body fat had little impact on BP levels in these children. Fat mass and lean mass may have a similar quantitative impact on BP in healthy-weight children.