Co-infection with tuberculosis (TB) and leprosy is thought to occur infrequently, but has been reported in settings highly endemic for both infectious diseases. We report for the first time a case where treatment for multidrug-resistant TB (MDR-TB) led to the ‘unmasking’ of clinically silent leprosy through the precipitation of a type-1 immunological reaction. Current treatment regimens for MDR-TB may contain a number of drugs, such as levofloxacin and clofazimine, which also have activity against M. leprae. A treatment regimen containing drugs active against both mycobacterial species may be used to achieve cure. Individual considerations on drug-drug interactions, potential additive toxicities and other comorbidities should be taken into account.