The concentrations of 14 chemical constituents in sera of 1,062 children and adolescents aged 4 to 20 years were measured and their 5th and 95th percentiles were calculated. The distribution of values for all constituents showed significant deviation from the gaussian when the results were combined, regardless of age and sex, except for magnesium. Although certain chemical constituents showed statistically significant relationships with age and sex, two additional criteria based upon the coefficient of variation of the method employed were utilized to judge the effectiveness of computing stratified reference values. After applying these corrections the reference values established were classified into three categories, viz. (1) those where the relationship to age and sex remained significant (inorganic phosphorus and creatinine); (2) those where the relationship to age only remained significant (total protein); (3) those where no significant relationship to age and sex was obtained (all other constituents).