Development of new tuberculosis (TB) vaccines and host-oriented therapy requires understanding mechanisms mediating protective antituberculous immunity. Antigen-specific Th1 lymphocytes have long been considered as the main correlate of TB protection. However, recent data do not confirm this concept. This article discusses debatable issues concerning the role for Th1 lymphocytes in antituberculous immunity, as well as their use as correlates of protection in preclinical and clinical studies assessing the effectiveness of new candidate TB vaccines.