['To quantify the efficacy of chemoprophylaxis against leprosy.', 'Literature searching of Medline and Embase databases, hand-searching of references and correspondence with investigators.', 'published papers relating to the prevention of leprosy and the use of chemotherapy in leprosy were identified for critical appraisal. Trials were selected and grouped into three categories according to study design and control groups.', 'the relative risks (RR) with 95% confidence intervals were calculated from the original data using a random effects model. To assess the cost-effectiveness of chemoprophylaxis, a further analysis of the rates of disease in the trial and control groups was done based on the numbers needed to be treated (NNT) to prevent one new case of leprosy.', 'A total of 14 trials were identified from 127 published papers on chemoprophylaxis of leprosy. The trials were categorized into randomized controlled trials, non-randomized controlled trials, and uncontrolled trials. The overall results of the meta-analysis shows that chemoprophylaxis gives around 60% protection against leprosy. The NNT are low in trials of household contacts.'] Is chemoprophylaxis effective in the prevention of leprosy in endemic countries : a systematic review and meta-analysis . MILEP2 Study Group . Mucosal Immunology of Leprosy?