Polycystic ovary syndrome (PCOS) is one of the most common reproductive health problems of women, causing irregular periods and potential infertility amongst other challenging symptoms. Effective treatment remains a significant challenge and is largely achieved through hormonal medication and lifestyle changes. This third edition covers the aetiology, pathology, impact on fertility and effective medical and surgical management. The content has been thoroughly revised in line with updated guidelines and research developments in the field. A new chapter on the patient’s perspective has been included, bringing valuable insight into the lived experience of the condition. Mood disorders and the psychological aspects of PCOS are also covered for the first time. This is a key reference for all clinicians involved in the care of patients with PCOS, including gynaecologists, IVF specialists and reproductive endocrinologists.