Even though the BCG vaccine is one of the most used vaccines in the world, tuberculosis is still a major problem worldwide. Research aimed at developing new vaccines against tuberculosis has become more goal-directed during the last 10-15 years, and there are now several vaccine candidates in clinical study phases I and II, that should be in phase III in 2010. It will then still take several years before we know whether a new vaccine will reduce the occurrence of tuberculosis. There are several promising vaccine candidates, but there is uncertainty whether they will be successful in reducing tuberculosis, as we do not have sufficient knowledge about protective immunity in tuberculosis. Today's vaccine candidates have been developed to protect against a few laboratory strains of the bacteria and will not protect against all strains. Estimations show that an effective vaccine against latent tuberculosis will give a rapid and considerable reduction in tuberculosis. The current vaccine candidates are however developed to protect against primary tuberculosis and not against reactivated latent tuberculosis. It is important to ensure an optimal experimental basis for new tuberculosis vaccines and to compare them so the best can be selected.