The Tuberculosis infection in recent years has become always more a threat. The failure in the attempt to stop it (O.M.S. Millennium Global Plan) brought to the revision of the world control strategy to at least contain this disease (The Global Plan to Stop TB 2006-2015). Due to these severe facts it is even more important now to elaborate more sensitive and specific methods to find out, as fast as possible, the infected cases. As of today, the main TB infection screening test is the Skin PPD test (Mantoux). Recently new tests for the population screening are in use; these tests are based on the evaluation of immunity cell-mediated. They (QFT-G) do not have the typical limits of the Skin Test and they are more suitable as serial tests and therefore more useful, according to us, in the screening programs of the TB infection in low prevalence countries, like Italy.