This review focuses on the available evidence for the use of levonorgestrel (LNG) intrauterine system (IUS) in women with chronic pelvic pain (CPP). We have searched MEDLINE, Pubmed, Embase, and the Cochrane electronic library with the keywords "chronic pelvic pain," "endometriosis," "Mirena IUS," and "levonorgestrel IUS" from 1956 through April 2008. Review articles, randomized trials, prospective cohort studies, and retrospective studies were analyzed and the available evidence included in this review. Case reports were not included in the analysis. Laparoscopic surgery was shown to be useful in clarifying the underlying cause in women with CPP, with 70% having abnormal findings at laparoscopy. Endometriosis, particularly deep infiltrating endometriosis, is found in 40% to 60% of women with dysmenorrhea. Laparoscopic excision of endometriosis was shown to be associated with improvement of symptoms in 70% to 80% of women. Up to 36% need repeated surgery during a 5-year period after the primary procedure. The absolute reduction in recurrence of dysmenorrhea in women who also had the LNG IUS inserted at the time of surgery was 35% (95% CI 9%-61%). The LNG IUS was shown also to reduce the blood flow in the uterine artery and the subendometrial spiral arteries. This may explain the reduction in primary dysmenorrhea in women who have the LNG IUS inserted. Insertion of the LNG IUS at the time of primary laparoscopic surgery in women with CPP caused by endometriosis has the potential to reduce postoperative pain scores. This medical approach is also a promising alternative to repeated laparoscopic surgery especially in those women who have continuing symptoms after laparoscopic excision of endometriosis. This nonsurgical option could potentially reduce the rate of repeated laparoscopies in women with CPP and, in turn, reduce overall intervention rates. Although growing evidence exists that the LNG IUS can be useful in this group of women, large randomized controlled studies are needed to validate its benefits in day-to-day practice.