Endometriosis is a common condition among women of childbearing potential in which ectopic endometrial tissue is found outside the uterine cavity. Neoangiogenesis plays a major role in the development of endometriotic implants. Some evidence suggests that a disorder in the balance of proangiogenic and antiangiogenic factors that favors the former is induced by local hypoxia and is mediated by the hypoxia-inducible factor-vascular endothelium growth factor pathway could partially explain the development of this condition in some women. 2-methoxyestradiol is a biologically active metabolite of estradiol having antiangiogenic action. Changes in estradiol homeostasis have been locally observed in endometriosis. In this review, we summarize current knowledge of endometriosis pathophysiology, in particular, the balance between local 2-methoxyestradiol production and angiogenesis, which could promote the development of endometriotic lesions. 2-Methoxyestradiol emerges as a promising new candidate for the treatment of endometriosis.