Our objective was to survey the outcome of treatment with levonorgestrel intrauterine system (Mirena LNG-IUS) at 6-18 months in a university affiliated tertiary referral hospital in adolescents. We report on a consecutive case series of 48 adolescents who had Mirena over 8 years as a day-case procedure between 2003 and 2008. The mean age was 15.3 years and all were of white British origin. The commonest indications were menorrhagia and dysmenorrhoea resistant to oral treatment. For 28/48 (58%), menstrual symptoms had a significant impact on quality-of-life; 45/48 (93.4%) reported ongoing significant improvement in their menstrual symptoms and 2/48 (4.2%) had the device removed within 4 months of insertion. We conclude that Mirena is a well tolerated and effective alternative for heavy periods +/- dysmenorrhoea in adolescents who do not respond to oral therapy.