Polycystic ovary syndrome (PCOS) is a common condition that affects multiple systems throughout a woman's life. It is now recognized as a metabolic syndrome involving hyperinsulinaemia, hyperlipidaemia, diabetes mellitus, and possible cardiac disease, in addition to the conventional features of hyperandrogenism, cosmetic issues, anovulation, infertility, endometrial cancer, and obesity. Diagnosis is based on peripubertal menstrual problems with clinical or biochemical hyperandrogenism, though the presence of polycystic ovaries on ultrasound is controversial. PCOS has a prevalence of 5%–10% in women of reproductive age, with polycystic ovaries found in 20%–25% of women. PCOS can manifest at any age, from childhood to later life, and may cause a range of symptoms including hirsutism, menstrual irregularities, infertility, glucose intolerance, and cardiovascular disease. While pelvic ultrasound is useful, many women without PCOS have polycystic ovaries. Testing for glucose intolerance and hyperlipidaemia is important, especially in obese women, as diabetes is common in PCOS. Lifestyle changes, including diet and exercise, are fundamental for treatment, and insulin-sensitising agents like metformin may be beneficial in cases of anovulatory infertility. Infertility in PCOS can be treated with diet and exercise, clomiphene citrate, ovarian drilling, or ovulation induction with gonadotrophins. In-vitro fertilisation should be avoided unless other indications are present. PCOS is often underdiagnosed, and clinicians should be aware that menstrual abnormalities are often associated with the condition. Many young women with these abnormalities are prescribed the oral contraceptive pill, which may mask the condition until they attempt to conceive. The pathogenesis of PCOS is poorly understood, but insulin resistance leading to hyperinsulinaemia is a primary defect. The cardinal feature is functional hyperandrogenism, with raised levels of androgens, oestrogen, insulin, and LH. This explains the classic presentation of hirsutism, anovulation, and glucose metabolism dysfunction. Insulin resistance is independent of obesity and may result from a specific genetic post-receptor defect. PCOS is associated with the metabolic syndrome, including obesity, insulin resistance, and dyslipidaemia. Obesity is common in women with PCOS, and insulin resistance is a key feature. Impaired glucose tolerance and type 2 diabetes are major complications in overweight women with PCOS. Dyslipidaemia is also common, with hypertriglyceridaemia, increased LDL cholesterol, and decreased HDL cholesterol. Cardiovascular disease is a concern due to the metabolic features of PCOS, though recent studies have raised doubts about the increased risk. Investigations for PCOS include a history and general examination, pelvic ultrasound, hormone assays, glucose testing, andPolycystic ovary syndrome (PCOS) is a common condition that affects multiple systems throughout a woman's life. It is now recognized as a metabolic syndrome involving hyperinsulinaemia, hyperlipidaemia, diabetes mellitus, and possible cardiac disease, in addition to the conventional features of hyperandrogenism, cosmetic issues, anovulation, infertility, endometrial cancer, and obesity. Diagnosis is based on peripubertal menstrual problems with clinical or biochemical hyperandrogenism, though the presence of polycystic ovaries on ultrasound is controversial. PCOS has a prevalence of 5%–10% in women of reproductive age, with polycystic ovaries found in 20%–25% of women. PCOS can manifest at any age, from childhood to later life, and may cause a range of symptoms including hirsutism, menstrual irregularities, infertility, glucose intolerance, and cardiovascular disease. While pelvic ultrasound is useful, many women without PCOS have polycystic ovaries. Testing for glucose intolerance and hyperlipidaemia is important, especially in obese women, as diabetes is common in PCOS. Lifestyle changes, including diet and exercise, are fundamental for treatment, and insulin-sensitising agents like metformin may be beneficial in cases of anovulatory infertility. Infertility in PCOS can be treated with diet and exercise, clomiphene citrate, ovarian drilling, or ovulation induction with gonadotrophins. In-vitro fertilisation should be avoided unless other indications are present. PCOS is often underdiagnosed, and clinicians should be aware that menstrual abnormalities are often associated with the condition. Many young women with these abnormalities are prescribed the oral contraceptive pill, which may mask the condition until they attempt to conceive. The pathogenesis of PCOS is poorly understood, but insulin resistance leading to hyperinsulinaemia is a primary defect. The cardinal feature is functional hyperandrogenism, with raised levels of androgens, oestrogen, insulin, and LH. This explains the classic presentation of hirsutism, anovulation, and glucose metabolism dysfunction. Insulin resistance is independent of obesity and may result from a specific genetic post-receptor defect. PCOS is associated with the metabolic syndrome, including obesity, insulin resistance, and dyslipidaemia. Obesity is common in women with PCOS, and insulin resistance is a key feature. Impaired glucose tolerance and type 2 diabetes are major complications in overweight women with PCOS. Dyslipidaemia is also common, with hypertriglyceridaemia, increased LDL cholesterol, and decreased HDL cholesterol. Cardiovascular disease is a concern due to the metabolic features of PCOS, though recent studies have raised doubts about the increased risk. Investigations for PCOS include a history and general examination, pelvic ultrasound, hormone assays, glucose testing, and