 The diagnosis of tuberculosis in children is a complex procedure. The commonly used test is the tuberculin skin test TST, which shows significant limitations such as cross-reactivity with the bacillus Calmette-Guerin BCG used for vaccination, and other environmental mycobacteria, the possible influence of age and the immunological status of the patient, the need to return to the hospital for the re-reading of the intradermal reaction. Since 2001, the Food and Drug Administration approved the first of a series of new tests, called Interferon-Gamma Release Assays IGRAs, based on the release of interferon gamma by sensitized lymphocytes in the blood of the patient. Among them, the QuantiFERON-TBGold In Tube QTF-GIT, Cellestis Limited, Carnegie, Victoria, Australia, is a highly specific test that measures, through an ELISA assay, the release of interferon-gamma production by lymphocytes in response to an antigenic challenge to Mycobacterium tuberculosis antigens. The antigens used in the test QTF-GIT ESAT-6, CFP-10 and the sequence of TB7.7 are in fact absent from the vaccine strain BCG and in most nontuberculous mycobacteria, giving to the QTF-GIT test greater specificity than TST. Moreover, being an in vitro test, it does not require a return visit to the reading of the result this is particularly important in screening of contacts, which is instead carried out in an instrument and therefore objective and, finally, thanks to the presence of an internal positive control, it is possible to evaluate the performance of tests and reduce possible technical errors. The QTF-GIT test gave significant results in adults in terms of sensitivity and specificity, as demonstrated by a large scientific literature, and is currently used in many hospitals, in combination with the TST, for the diagnosis of tuberculosis. Since September 2012, also the Siena University Hospital introduced the QTF-GIT assay as a diagnostic test for tuberculosis diagnosis in healthcare workers and in inpatient or outpatient tested positive TST requiring detailed diagnostic investigation eg. Previous BCG vaccination, suspected atypical mycobacteriosis, eruptive events or other skin changes that contraindicate performing intradermal reaction. 