Postnatal virilization is reported in a prepubertal girl with onset at age 6 years. The pattern of steroid excretion, response to ACTH stimulation and decadron suppression was as seen with congenital adrenal hyperplasia secondary to a defect in 21-hydroxylation. Because of the similar age of onset of previously reported cases it is suggested that this postnatal form most likely represents a variant of the congenital variety rather than an acquired disorder.