The objectives of this study were to evaluate the bleeding patterns and clinical performance during the first 2 years of use of an intrauterine system releasing 20 microg/day of levonorgestrel (LNG-IUS, Mirena). Two-hundred-fifty-six women accepted use of Mirena from April 1998 through September 1998. The gross cumulative discontinuation rate due to pregnancy and expulsion were significantly higher in women who used the device because of heavy bleeding. There was one pregnancy at the 15th month of use after an inadvertent expulsion of the device. The continuation rate was 66.2 at the end of the second year. Forty-four percent of women reported amenorrhea at the 6th month of use. This rate maintained stability at 50% after 12 and 24 months of use. Spotting was present in 25% of the users at 6 months, decreasing to 8% and 11% at 18 and 24 months, respectively. Oligomenorrhea was described by one-quarter of women and was similar at each observation period. Removals due to menstrual bleeding problems were concentrated in the first 6 months of use and mostly due to amenorrhea or menorrhagia. In conclusion, LNG-IUS showed a high contraceptive efficacy and a good continuation rate up to 2 years. In addition, a reduction of blood loss was observed a few months after insertion.65129-32