In vitro assays that measure the interferon gamma production by T cells incubated with specific antigen of Mycobacterium tuberculosis may be useful in the diagnosis of tuberculosis in children. Compared to Mantoux test, these tests are easier to perform and have a greater specificity, especially because they do not cross-react with BCG vaccine and with most of environmental Mycobacteria. However, their sensitivity is not well evaluated in children. To date in pediatrics, they can be associated with Mantoux test for the diagnosis of active tuberculosis. In the diagnosis of latent tuberculosis infection, larger studies with commercial kits are required.