This chapter provides a detailed account of the chronology of immunopathogenesis of TB and the underlying molecular mechanisms, immune effector mechanisms against M. tuberculosis, acquired T-cell mediated immune mechanism and role of CD4+ and CD8+ T-cells. Furthermore, cytokines, chemokines and granuloma formation are also discussed at length. This chapter also provides a unique overview regarding the T-cell subsets with an immunoregulatory role, immune evasion by M. tuberculosis and immunomodulators in TB