To the Editor: The purpose of newborn screening (NBS) for congenital adrenal hyperplasia (CAH) due to 21α-hydroxylase deficiency is the early identification of newborns with the classic salt-wasting (SW) and simple-virilizing (SV) forms to avoid a potentially life-threatening adrenal or salt-wasting crisis. Cases of classic CAH missed by NBS (false-negatives) are not well documented.1