ABSTRACT.: Polycystic ovary syndrome (PCOS) affects 6–12% of reproductive-aged women 1 2. The condition is now recognized to have its beginnings in the perinatal period and may be exacerbated by environmental and lifestyle influences in the peripubertal timeframe. The consequences of PCOS extend beyond menopause. The paradigm of PCOS is one of a life-long condition with multiple effects at key developmental periods, requiring assessment and management in the primary care setting. The definition of PCOS has evolved over time but essentially includes assessment of ovulatory function, androgen status, and ovarian morphology. The pathophysiology of PCOS is still not entirely understood, and clinical presentations based on the diagnostic criteria encompass a wide spectrum. Evidence of familial inheritance of the syndrome exists, but genetic studies thus far have not isolated a susceptibility gene to explain the disease in most individuals. Increasing evidence points to the role of epigenetic factors in the intrauterine environment and postnatal environmental influences that may change the trajectory of PCOS. A primary characteristic of PCOS is hyperandrogenism, which, in most cases, is linked to hyperinsulinemia. Resultant metabolic changes include an increased risk of diabetes. Polycystic ovary syndrome alters gonadotropin dynamics, which results in ovulatory dysfunction and, in many cases, infertility. Obesity is a common finding in patients with PCOS, and the prevalence of PCOS increases when obesity is present in high frequency in the population. Diagnosis remains primarily a clinical one with elimination of other causes of oligo-ovulation or hyperandrogenism. The primary features of PCOS, including androgen excess, menstrual irregularity, and infertility, are best treated based on a symptomatic approach. Oral contraceptives remain the mainstay of management of androgen excess and menstrual irregularities. The association between PCOS and metabolic disorders has been recognized, and patients with PCOS should undergo screening for diabetes mellitus and cardiovascular risk factors. Prevention of these complications will be reviewed in this monograph. Lifestyle modification remains a mainstay of treatment, with metformin therapy useful for glucose intolerance and metabolic dysfunction. The best opportunities for intervention present when the condition is first recognized in the adolescent patient because this may represent the best chance for long-term benefit. A multidisciplinary approach often is helpful to address the concerns regarding obesity and hyperandrogenism with attention to the increased risk of depression and anxiety seen in patients with the condition.