We performed gonadotropin releasing hormone agonist (GnRHag) tests on 23 consecutive hyperandrogenic girls 9.9-17.5 years of age who were referred to our pediatric endocrinology clinic with symptoms suggestive of PCOS. They were compared to contemporaneously studied groups of adult normal and hyperandrogenic women. We found that hyperandrogenic adolescents had clinical and endocrine features similar to those of hyperandrogenic adults. However, there were some noteworthy unique features of adolescent hyperandrogenism, such as presentation in mid-childhood with premature pubarche and the occasional diagnosis before the age of 10 years. Some differences between adolescents and adults were statistically significant, for example, pelvic ultrasonography was not as helpful in the diagnosis of FOH as it is in adults. Nevertheless, a number of questions about the development of the ovarian dysfunction remain to be answered. For example, we are unable to diagnose ovarian dysfunction before puberty or in early puberty, and the relationship of "physiologic adolescent anovulation" to PCOS remains to be defined.