Prevalent since pre-history, human tuberculosis - caused by the pathogen Mycobacterium tuberculosis - remains a major source of death worldwide. Moreover, increasing drug resistance poses the threat of disease resurgence. However, the expanding application of genomic techniques is providing new avenues for combating this old foe. Whole-genome sequencing, comparative genomics and systems biology are generating new insights into the origins and ongoing evolution of M. tuberculosis, as well as the molecular basis for its pathogenicity. These have important implications for our perspective of the disease, development of new drugs and vaccines, and treatment of patients using existing therapeutics.