Polycystic ovary syndrome (PCOS) is the most common endocrinopathy affecting women of childbearing age. Its complex pathophysiology includes genetic and environmental factors that contribute to insulin resistance in patients with this disease. The diagnosis of PCOS is primarily clinical, based on the presence of at least two of the three Rotterdam criteria: oligoanovulation, hyperandrogenism, and polycystic ovaries on ultrasonography. PCOS is often associated with hirsutism, acne, anovulatory menstruation, dysglycemia, dyslipidemia, obesity, and increased risk of cardiovascular disease and hormone-sensitive malignancies (e.g., at least a twofold increased risk of endometrial cancer). Lifestyle modification, including caloric restriction and increased physical activity, is the foundation of therapy. Subsequent management decisions depend on the patient's desire for pregnancy. In patients who do not want to become pregnant, oral contraceptives are first-line therapy for menstrual irregularities and dermatologic complications such as hirsutism and acne. Antiandrogens such as spironolactone are often added to oral contraceptives as second-line agents. In patients who want to become pregnant, first-line therapy is letrozole for ovulation induction. Metformin added to lifestyle management is first-line therapy for patients with metabolic complications such as insulin resistance. Patients with PCOS are at increased risk of depression and obstructive sleep apnea, and screening is recommended.