OBJECTIVE:To evaluate the efficacy, acceptability, and possible side effects of a levonorgestrel-releasing intrauterine system for menorrhagia. METHODS:Sixty-three women with menorrhagia but without uterine enlargement, endometrial hyperplasia with atypia, or endometrial carcinoma were enrolled in this prospective, open, nonrandomized clinical trial. An intrauterine system releasing 20 microg/day of levonorgestrel (LNG-IUS; Mirena, Shering, Finland) was inserted in the postmenstrual phase. Menstrual pattern, number of bleeding days, and subjective and objective estimation of menstrual blood loss using a pictorial blood loss assessment chart (PBAC) were recorded before insertion and at specific intervals for 4 years. Hemoglobin levels and endometrial thickness were evaluated at baseline and at 12 months. Treatment continuation and hysterectomy rates were noted as well as side effects. RESULTS:The device was expelled spontaneously in 6 patients (9.52%) and removed prematurely in 9 patients (14.3%); 3 patients (4.8%) were lost to follow-up; and 45 patients (71.4%) continued with the LNG-IUS. Menorrhagia was cured in 35 (77.7%) of these 45 patients at 3 months and in all patients at 36 months. There was a significant decrease in the mean number of bleeding days (P=0.01) and PBAC score (P=0.00) at 1 month, and the decrease continued with treatment duration. The subjective blood loss reduction was considerable as well, and at 12 months the mean+/-SD rise in hemoglobin concentration was 1.06+/-1.7 g/dL (P=0.000). Endometrial thickness was decreased by 3.4+/-3.53 mm (P=0.0001) at 12 months. The most common side effect was intermenstrual spotting during the first 6 months, and 18 patients (28.57%) developed amenorrhea. CONCLUSION:Using the LNG-IUS is an effective and well-accepted option overall for the medical management of menorrhagia.