This study evaluated the efficacy and feasibility of long-term use of levonorgestrel releasing intrauterine system (LNG-IUS) in endometriosis patients after using LNG-IUS for >5 years as their postoperative maintenance therapy.Data were obtained retrospectively from patients who maintained medical therapy for >5 years after surgical treatment of endometriosis from January 2008 to April 2015. Patients were divided into study group and control group according to the type of medication; the study group consisted of patients who received LNG-IUS as maintenance therapy, and patients in the control group received combined oral contraceptives (ethinyl estradiol 20 μg and drospirenone 3 mg) or dienogest 2 mg.A total of 263 patients (94 patients in the study group, 169 in the control group) were included in the study. 91.5% (86/94) of the patients in the study group maintained the treatment for >5 years, whereas only 21.9% (37/169) of patients in the control group maintained the treatment for >5 years.LNG-IUS significantly decreased the pain score for non-cyclic pelvic/back pain (from 4.0 ± 1.6 to 0.6 ± 1.3, P < .001), dysmenorrhea (from 6.5 ± 1.7 to 6.5 ± 1.7, P < .001), and dyspareunia/dyschezia (from 6.5 ± 1.7 to 1.3 ± 1.4, P = .006) after 1 year, and the effect was persistent for 10 years (P < .01). When compared with control group, the effect on pain reduction was comparable to the oral contraceptives or dienogest, with less systemic side effects such as mood change or nausea.LNG-IUS for >5 years as a postoperative maintenance therapy for endometriosis patients is an effective and feasible treatment that shows significant effect on pain reduction with less systemic side effect compared with other types of treatment. Therefore, LNG-IUS can be recommended as a long-term postoperative therapy for endometriosis patients who do not plan to become pregnant for several years.