Objective To investigate the correlation of metabolism disturbance of oxygen free radical(OFR) with endometriosis and endometrioma, to provide an evidence for the diagnosis and treatment. Methods (1) The lipid peroxide (LPO), selenium (Se), superxide dismutase (SOD) and vitamine E (VE) levels were respectively in the vein blood, ovary tissue of the chocolate cyst wall and chocolate cyst fluid in 32 operated patients with endometriosis (endometriosis group). (2) The levels above were determined seperately in 23 operated patients with endometrioma (endometrioma group) and 30 cases of hysteroma (control group). Results (1)The LPO levels in vein blood and ovary tissue of endometriosis group were (6 357?1 251) ?mol/L and (3 735?1 546) nmol/g protein. Which significantly higher than those of control group ( P 0 05). Conclusion The endome triosis and endometrioma is related to the produce or metabolistic inbalance of oxygen free radical, and so to the increasing of lipid peroxide.