Polycystic ovary syndrome (PCOS) is a syndrome, which can be defined as a group of recognisable patterns of symptoms or abnormalities that indicate a particular medical situation. The current definition of PCOS requires the presence of two of the following three conditions: (i) oligo- and/or anovulation; (ii) clinical and/or biochemical signs of hyperandrogenism; and (iii) polycystic ovaries--and the exclusion of other aetiologies. It is generally accepted that the prevalence of PCOS is approximately 5-10%, and that of polycystic ovaries alone is 21-23%. Other features of PCOS are obesity, insulin resistance, impaired glucose tolerance and type 2 diabetes mellitus, dyslipidaemia, cardiovascular disease, obstructive sleep apnoea and infertility. An approach to a patient with possible PCOS should be directed towards making a diagnosis and screening for associated endocrine abnormalities. Therapeutic interventions are directed towards addressing the needs of the patient at present and towards preventing long-term complications of the syndrome. Body mass index, which is a primary mediator in the relationship between PCOS and health-related quality of life in obese PCOS adolescents, may play a similar role in other PCOS patients. Any intervention directed at reducing central obesity will not only improve quality of life but also correct hyperinsulinism and improve fertility and lipid and androgen profiles. It is also the only currently available intervention that can have a lifelong impact on reducing possible long-term complications of the syndrome. Lifestyle modification is the cardinal intervention. Pharmacological treatments are available for specific indications. Infertility can be treated with clomifene (clomiphene citrate), metformin, gonadotropins or surgery to the ovaries. Cyproterone (alone or in combination with ethinylestradiol) and spironolactone are the main drugs used in the treatment of hirsutism. Other drugs that can be considered include flutamide, ketoconazole and finasteride. Women with PCOS require ongoing surveillance to detect impaired glucose tolerance, hyperlipidaemia, endometrial hyperplasia and consequent complications. Obese women, in particular, require regular glucose tolerance testing because of the potential for rapid progression from normal to impaired glucose tolerance and diabetes. The focus of this article is the epidemiology, diagnosis and management of this common endocrine disorder. Diagnostic and co-morbid features are discussed separately to facilitate understanding of PCOS. Symptom-directed strategies, as well as short- and long-term goals of treatment, are outlined.