This report is a review of the medical literature on the use of the levonorgestrel-releasing intrauterine system (LNG-IUS) in women with endometriosis, adenomyosis, cyclic pelvic pain and dysmenorrhea. A review was carried out using the MEDLINE and EMBASE databases to evaluate the use of LNG-IUS in women with endometriosis and adenomyosis. Nine studies were identified, only two of which were randomized clinical trials. One compared the insertion of LNG-IUS after surgery with expectant conduct and the other compared the use of the device with a GnRH analogue (GnRH-a). All studies reported an improvement in pelvic pain and dysmenorrhea, and a reduction in menstrual bleeding. One study found an improvement in the staging of the disease at 6 months of use, and the studies that evaluated the use of LNG-IUS in women with adenomyosis reported a reduction in uterine volume. Furthermore, the only study in which women were followed up for 3 years after insertion found improvement in pelvic pain at 12 months of use. However, there was no improvement after that period. The use of LNG-IUS is an alternative for the medical treatment of women suffering from endometriosis, adenomyosis, chronic pelvic pain or dysmenorrhea, but experience is limited and long-term studies are necessary to reach definitive conclusions. However, for women who do not wish to become pregnant, this device offers the possibility of at least 5 years of treatment following one single intervention.75S134-9