Endometriosis is defined by presence of endometrial glands and stroma outside the uterine cavity and it affects approximately 5%-10% of women of reproductive age. Although endometriosis is usually considered to be due to retrograde menstruation, the true pathogenesis of this disease remains poorly understood. Endometriosis is associated with an inflammatory response and this inflammation leads to endothelial dysfunction and might even lead to carcinogenesis. Here, we review our current understanding of the role of inflammatory processes in the pathogenesis of endometriosis.