This paper was designed to examine appropriateness of equations for calculating percent body fat from body density. Subjects were 141 boys and 163 girls aged 9-14 years. Body density (Db) was determined by underwater weighing (UW). Residual volume was measured by helium dilution technique (COMP-100, Fukuda Co.). Percent body fat (%fat) was calculated from the formula of Lohman et al. or Brozek et al. The %fat ranged between -0.52% and 44.20% in boys and between 4.94% and 47.44% in girls when the formula of Lohman et al. was used, while the range was 7.00%-45.56% in boys and 11.71%-48.35% in girls when the formula of Brozek et al. was used. In order to examine which formula is more appropriate for the assessment of body composition in boys and girls, %fat values calculated from both formulae were compared. Comparison criterion was essential lipid (boy: 3-5%, girl: 9%). The number of boys whose %fat was 5% or below was 18/141 (12.8%) and the number of girls whose %fat was 10% or below was 19/163 (11.7%) when the formula of Lohman et al. was applied, while the minimum value was 7.00% in boys and 11.71% in girls when the formula of Brozek et al. was utilized. From these results, it is suggested that the formula of Brozek et al. may be more appropriate than the formula of Lohman et al. for the estimation of %fat in boys and girls.