Background: Disruption of ovulation occurs in different types of clinical infertility. The World Health Organization (WHO) has provided a classification of ovulation disorders. This review focuses on WHO group 2 anovulation. Methods: Searches were performed in Medline/PubMed and EMBASE. Each subject summary was presented to the European Society of Human Reproduction and Embryology (ESHRE) Workshop Group, where omissions or disagreements were resolved by discussion. Results: Disorders resulting in ovulatory disturbances are a relatively common cause of infertility. They occur most frequently in the context of WHO group 2 anovulation as reflected, for example, in the polycystic ovary syndrome (PCOS). The aetiology of PCOS remains unclear but evidence exists for a multifactorial origin with a genetic predisposition. Women with PCOS show an increased time to pregnancy but their eventual family size is not necessarily reduced. Also their frequency of miscarriage does not appear increased. Clomiphene citrate is still the first-line treatment in subfertile anovulatory patients with PCOS, with gonadotrophins and laparoscopic ovarian surgery as second-line options. Aromatase inhibitors show promising results. Conclusions: Long-term health risks in patients with WHO group 2 anovulation demand their general health be monitored, even after their reproductive needs have been fulfilled. Metabolic and cardiovascular risk prevention in women with PCOS should start as early as possible. It is not easy to analyse the possible role of PCOS, independent of obesity, metabolic syndrome, insulin resistance and diabetes, on long-term health.