Abstract： Objective To evaluate the efficiency of levonorgestrel-releasing intrauterine system (LNG-IUS) in the treatment of recurrent endometriosis after conservative surgery or conservative surgery combined with medical treatment. Methods Twenty-three patients with recurrent endometriosis after conservative surgery or conservative surgery combined with medical treatment were treated by LNG-IUS. All patients rejected further operation and had no desire of fertility. The visual analogue scale (VAS) scores of pain, menstrual model, weight and serum CA125 level and the volume of ovarian endometriotic cysts before and after 3, 6, 12, 24 and 36 months of treatment were recorded and compared. Results ( 1 ) VAS score:after 12 months of using LNG-IUS, dysmenorrheal, chronic pelvic pain or dyspareunia were relieved significantly. VAS score were dropped from 5.9 ± 2. 3,4. 3 ± 2.0 to 1.0 ± 0. 7,1.4 ± 1. 1 ( P ＜ 0. 01 ). ( 2 )Volum of cysts :after 6 months of using LNG-IUS, the volume of recurrent ovarian endometriotic cysts in 11 patients were reduced from ( 11.4 ± 6. 1 ) em3 to ( 5. 5 ± 3.4 ) em3 significantly ( P ＜ 0. 01 ). At 12 months of follow-up, it suggested that 2 patients' ovarian endometriotic cysts disappeared. At 24 months follow-up,9 patients ovarian endometriotic cysts disappeared ( 3 ) CA125: serum CA125 decreased from ( 65.5 ± 19. 6 )kU/L to (42. 1 ± 13.6) kU/L at 6 months after treatment remarkably (P ＜ 0. 01 ). Continued to decrease after 12 months and then become steady. Irregular bleeding and spotting was the main side effects, weight gain was also observed in few patients. Conclusions LNG-IUS could be used in treatment of recurrent endometriosis after conservative surgery or conservative surgery combined with medical treatment effectively. It could relieve pain, reduce the level of CA125 and decrease the size of ovarian endometriotic cysts. LNG-IUS seems to be an effective, safe, and long term treatment for endometriosis with fewer side effects and better compliance.