Polycystic ovary syndrome is the most common endocrinopathy among reproductive-aged women in the United States, affecting approximately 7% of female patients. Although the pathophysiology of the syndrome is complex and there is no single defect from which it is known to result, it is hypothesized that insulin resistance is a key factor. Metabolic syndrome is twice as common in patients with polycystic ovary syndrome compared with the general population, and patients with polycystic ovary syndrome are four times more likely than the general population to develop type 2 diabetes mellitus. Patient presentation is variable, ranging from asymptomatic to having multiple gynecologic, dermatologic, or metabolic manifestations. Guidelines from the Endocrine Society recommend using the Rotterdam criteria for diagnosis, which mandate the presence of two of the following three findings- hyperandrogenism, ovulatory dysfunction, and polycystic ovaries-plus the exclusion of other diagnoses that could result in hyperandrogenism or ovulatory dysfunction. It is reasonable to delay evaluation for polycystic ovary syndrome in adolescent patients until two years after menarche. For this age group, it is also recommended that all three Rotterdam criteria be met before the diagnosis is made. Patients who have marked virilization or rapid onset of symptoms require immediate evaluation for a potential androgen-secreting tumor. Treatment of polycystic ovary syndrome is individualized based on the patient's presentation and desire for pregnancy. For patients who are overweight, weight loss is recommended. Clomiphene and letrozole are first-line medications for infertility. Metformin is the first-line medication for metabolic manifestations, such as hyperglycemia. Hormonal contraceptives are first-line therapy for irregular menses and dermatologic manifestations.