Anthropometric data on children exposed to the atomic bomb were collected by the Atomic Bomb Casualty Commission as part of a study of long-term effects of the bomb upon human beings. These data have been analyzed, using multivariate techniques with anthropometric measurements as variables, for differences in size, growth rate, and change of growth rate among groups graded roughly according to radiation exposure received. Significant differences were observed among the groups, at all age levels studied, according to size; and among the groups in the postpubertal age levels, according to growth rate and change in growth rate.