Female reproductive system is vulnerable to the harmful effects of reactive oxygen species (ROS) that damage proteins, lipids, and DNA structure. Oxidative stress is a key factor for progression of endometriosis. Many theories have been elaborated so far to clarify endometriosis pathogenesis and oxidative stress, a result of increased production of free radicals or depletion of the body's endogenous antioxidant defense, has been implicated in its pathogenesis.