Polycystic ovarian syndrome (PCOS) is believed to be the most common endocrinopathy affecting women in the reproductive age group. It is increasingly being recognized in adolescent girls who seek treatment for signs and symptoms of hyperandrogenism and is frequently but not universally associated with obesity. A major component of the syndrome is insulin resistance or hyperinsulinemia, which is proposed to play a pathophysiologic role. There are convincing in vitro, in vivo, and therapeutic intervention studies to suggest that insulin stimulates ovarian androgen secretion leading to functional ovarian hyperandrogenism. A significant proportion of patients with PCOS also have functional adrenal hyperandrogenism, which is also thought to be mediated through insulin-stimulating adrenal androgen secretion. Besides its gynecologic consequences, PCOS is associated with increased risk for impaired glucose tolerance and type 2 diabetes, dyslipidemia, and cardiovascular sequelae. These derangements are present early in the course of the PCOS in the adolescent age group. Retrospective clinical data would suggest that in some cases premature adrenarche may herald future PCOS in adolescents. Though there are no robust epidemiologic data, there is an overall clinical impression that PCOS is increasing among adolescents. It is tempting to speculate that the epidemic of obesity afflicting US children may be the driving force. Obesity with its resultant insulin resistance or hyperinsulinemia may trigger or unmask the syndrome in genetically predisposed individuals. It remains to be determined if insulin sensitizers play a role in the management of PCOS in the pediatric age group.