Over the last decade, molecular biology techniques for identifying mycobacteria in pulmonary secretions have become more and more sensitive and rapid, even in smear negative samples. Nuclear amplification techniques also allow the rapid detection of resistance to first or second line anti-tuberculous drugs. The sensitivity of these techniques for non respiratory samples is yet to be determined. The diagnosis of latent tuberculous infection (LTBI) has also increased in sensitivity, specificity and positive predictive value through the use of interferon-γ release assays (IGRAs), which are tending to replace the tuberculin skin test, except for children aged under five. These tests, however, do have limitations which are important for the clinician; especially their inability to distinguish active from latent tuberculosis and their inability, in most circumstances, to exclude a diagnosis of active TB.