Abstract A modified radial immunodiffusion procedure was used to quantitate normal immunoglobulins IgG, IgA, and IgM in approximately 300 normal healthy age-defined children. The results were recorded as both, the percentage of the adult level and the Student 2 sample t test to indicate significance of difference from the adult level. Both values were used in our comparisons with other investigators' results. Adult levels of IgM, and IgG were attained at ages of 2 and 7 years, respectively, while IgA was not realized in our studies at the upper age level used, namely 13 years. Comparative increases and decreases of these 3 immunoglobulins over the 13-year span were also discussed.