Tuberculosis is one of the biggest global health problems. One-third of the world's population (2 billion) is latently infected with tuberculosis. The tuberculin skin test is commonly used to diagnose tuberculosis infection. This test has poor specificity and sensitivity, cross-reactivity with bacille Calmette-Guérin vaccination and many environmental mycobacteria, and poor sensitivity (only 75-90% in active tuberculosis). Mycobacterium tuberculosis activates a strong T cell-mediated immune response. That is why, a better marker for tuberculosis infection could be the presence of mycobacteria specific interferon-gamma-secreting T cells. These cells can be identified in blood or any other sample, which contains T cells. The test specificity is 99.9% (in low-risk control groups), and the sensitivity is 97.2% (in subjects with culture-confirmed active disease). New in vitro diagnostic test of tuberculosis, based on tuberculosis-induced immunological mechanisms, seems to be more specific and useful as previous methods.