The specificity of the new blood test for detecting latent tuberculosis infection (IGRA) is considerably superior to that of the tuberculin skin test. This has been demonstrated by many studies in different populations. The sensitivities of both tests are similar, especially when testing persons with close contacts. In May 2007 the new DZK recommendations for environmental contact tracing in tuberculosis were published. One of main modifications is the recommendation of the IGRA to confirm a positive tuberculin skin test. As it has been using the IGRA since October 2005, the tuberculosis information centre in Hanover has access to a considerable amount of data. In this report our practical experience with the test is described, especially application, reduction of costs for diagnosis and staff, benefit for patients (decreased X-ray exposition) and easier decision-making for preventive treatment.