In Reply.—We appreciate Drs Block and Chesney's comments and would like to note that the values given in their letter (0.486 and 0.475 g/cm for boys and girls, respectively) at age 6 years are not the values that appear in the reference they give.1 However, though less striking, the correct values of 0.466 and 0.436, respectively, in the reference noted are still significantly different from our value of 0.356 g/cm. The difference is within 2 SDs of our mean. The difference in bone mineral content between the two populations is of concern to us, as well, and may indeed represent differences in ethnicity, diet, exercise, and other unknown factors. Until more information becomes available, it would appear prudent to use region-specific, in addition to race-, age-, and sex-specific, norms to evaluate bone mineral content in children.