A 17-yr-old female presented with marked menstrual irregularities since menarche at age 13 yr and severe hirsutism, particularly facial, since puberty. Her disorder was shown to be related to a mild 21-hydroxylase deficiency and she was diagnosed to have an attenuated (so-called acquired) form of congenital virilizing adrenal hyperplasia. HLA typing and ACTH testing of her parents and siblings provided evidence of a linkage between HLA and 21-hydroxylase deficiency loci. Similar observations have been made previously for the salt-losing and simple virilizing forms of congenital virilizing adrenal hyperplasia, suggesting that these two as well as the attenuated forms are allelic in regard to the 21-hydroxylase deficiency gene.