This article, published in the Medical Journal of Australia in 2004, provides a comprehensive overview of Polycystic Ovary Syndrome (PCOS). Initially known as Stein–Leventhal syndrome, PCOS is now recognized as a metabolic syndrome involving hyperinsulinemia, hyperlipidemia, diabetes mellitus, and potentially cardiac disease, in addition to androgen excess, cosmetic issues, anovulation, infertility, endometrial cancer, and obesity. The diagnostic criteria for PCOS are discussed, emphasizing the controversy surrounding the presence of polycystic ovaries on ultrasound as a key criterion. The prevalence of PCOS is estimated to be 5%–10% in women of reproductive age, with polycystic ovaries found in 20%–25% of women in some studies. The pathogenesis of PCOS is poorly understood but is thought to involve insulin resistance leading to hyperinsulinemia and functional hyperandrogenism in the ovaries. The condition can affect women at all ages, from fetal life to old age, with potential complications including endometrial hyperplasia and cancer, metabolic syndrome, and cardiovascular disease. Management strategies include treating symptoms such as hirsutism, menstrual dysfunction, and infertility, often through lifestyle changes, medication, and, in some cases, surgery or gonadotrophin treatment. The article also highlights the importance of early diagnosis and ongoing surveillance for complications, particularly in obese women, and provides useful resources for patients and healthcare providers.This article, published in the Medical Journal of Australia in 2004, provides a comprehensive overview of Polycystic Ovary Syndrome (PCOS). Initially known as Stein–Leventhal syndrome, PCOS is now recognized as a metabolic syndrome involving hyperinsulinemia, hyperlipidemia, diabetes mellitus, and potentially cardiac disease, in addition to androgen excess, cosmetic issues, anovulation, infertility, endometrial cancer, and obesity. The diagnostic criteria for PCOS are discussed, emphasizing the controversy surrounding the presence of polycystic ovaries on ultrasound as a key criterion. The prevalence of PCOS is estimated to be 5%–10% in women of reproductive age, with polycystic ovaries found in 20%–25% of women in some studies. The pathogenesis of PCOS is poorly understood but is thought to involve insulin resistance leading to hyperinsulinemia and functional hyperandrogenism in the ovaries. The condition can affect women at all ages, from fetal life to old age, with potential complications including endometrial hyperplasia and cancer, metabolic syndrome, and cardiovascular disease. Management strategies include treating symptoms such as hirsutism, menstrual dysfunction, and infertility, often through lifestyle changes, medication, and, in some cases, surgery or gonadotrophin treatment. The article also highlights the importance of early diagnosis and ongoing surveillance for complications, particularly in obese women, and provides useful resources for patients and healthcare providers.