This chapter gives an overview of tuberculosis diagnostics. The infection by Mycobacterium tuberculosis (MTB) affects near one-third of the world population, and kills almost 2 million people each year. The most desirable characteristics of a diagnostic tool for tuberculosis are affordability, rapidity and accuracy. Clinical screening and optimizing sample collection are key steps in the diagnostic process. This chapter also covers the diagnosis of latent tuberculosis infection and diagnosis of active pulmonary tuberculosis. The gold standard for the diagnosis of active pulmonary TB is the culture isolation of the organism on sputum, bronchial or gastric aspirates. A significant progress in the diagnosis of latent tuberculosis infection (LTBI) has been obtained through the creation of in vitro blood tests based on specific cell-mediated immune response.