BACKGROUND The levonorgestrel intrauterine system (LNG-IUS) combines a uterine foreign body and the continuous release of low-dose levonorgestrel for contraception. Its influence on the rate of vulvovaginal infections and flora disturbance is insufficiently known, but important for contraceptive advice in women, especially those who develop recurrent vaginosis or Candida vulvovaginitis. METHODS Slides of 286 women who had a Pap smear taken before and 1 to 2 years after placement of a LNG-IUS were blindly reviewed for the presence of abnormal vaginal flora (AVF), bacterial vaginosis (BV), aerobic vaginitis (AV) and Candida vaginitis (CV). RESULTS Prior to insertion, there were no differences in vaginal flora abnormalities between women using different kinds of contraception. LNG-IUS users did not have different rates of AVF, BV, AV or CV, but the general risk to develop any infection was increased. Uterine bleeding after insertion did not seem to predict a different flora type. CONCLUSIONS We found that Pap smears suggested more vaginal infections after 1 year of LNG-IUS use than prior to insertion of the device.