Endometriosis, a common cause of morbidity, affects 10% of women of reproductive age. In this review we focus on the new developments in pathogenesis, diagnosis and treatment options, reviewing the literature published about this enigmatic disorder over the past three years. More specifically, new theories of the pathogenesis of the syndrome of Sampson and Cullen are discussed. The new era of genomics may characterize endometriosis and transform clinical management of the disease. Literature suggesting that endometriosis may have an environmental origin is reviewed. New approaches to medical therapy of endometriosis have been developed, including the levonorgestrel-releasing intrauterine device, aromatase inhibitors, immunomodulatory drugs, angiogenesis inhibitors, selective estrogen and progesterone receptor modulators, and statins. Subfertility is another well-known result of endometriosis and often complex decisions must be made regarding management of the endometriosis patient who wishes to conceive. Laparoscopic surgery and assisted reproduction--with or without gonadotropin-releasing hormone-agonist treatment--are reviewed. Finally we speculate about new developments in the field of endometriosis in the coming three years.