Endometriosis is one of the most frequent benign diseases in women of child-bearing age. The main symptoms are chronic upper abdominal pain and infertility. However, the aetiology and pathogenesis of endometriosis are as yet insufficiently clarified. Thus, therapy is mainly symptomatic with laparoscopic surgery being the gold standard. The aim of drug therapy is to achieve a hypo-oestrogenic condition. In cases of severe endometriosis and a desire to have children there is often an indication for assisted reproduction. The present article illustrates almost all current aspects on the diagnosis of and therapy of endometriosis. From the clinical viewpoint, emphasis is placed on the rare cases of deeply infiltrating endometriosis that are, however, accompanied with a high morbidity. Current therapeutic options in cases of infertility are also presented in more detail. Furthermore, special attention is paid to the latest research results from both clinical and basic research fields in order to demonstrate our current knowledge on the pathogenesis and, where possible, potentially related therapeutic options.