Successful management of infertility involves the use of appropriate diagnostic tests and treatments, and knowledge of prognostic factors such as age of the female partner and duration of infertility. The assessment of infertility may reveal disorders that cause morbidity in the normally fertile population, which might or might not contribute to the infertility. Endocrine dysfunction is a significant cause of infertility due to amenorrhoea and dysfunctional uterine bleeding, and hirsutism is a familiar problem in the normal population. Some genetic abnormalities cause infertility in males and females and create implications for the progeny of infertile couples. Sexually transmitted diseases cause illness and healthcare expenditure among young adults, and can also result in tubal infertility. Congenital disorders of the uterus and fibromyomas are not rare and they are frequently asymptomatic, but in some cases uterine anomalies may contribute to infertility and pregnancy loss. Autoimmunity underlies some common diseases, especially among females, and it can also be associated with pregnancy loss. When such widely distributed factors are identified during the diagnostic assessment of subfertile couples, it is important to distinguish between a coincidental association and a specific relationship to the infertility.