Introduction: Tuberculosis is still one of the leading public health problems despite the prevention measures, diagnosis and treatment methods as well as the national TB suppression program. Treating and actively seeking people with LTBI is the path to eradicating the disease. Objectives: 1. To investigate the role and the benefit of IGRA (Interferon gamma release assay) tests in screening for tuberculosis, 2. To show the most prominent epidemiological characteristics of M. tuberculosis infection, 3. To investigate the incidence and prevalence of M. tuberculosis infection using the QFT-Plus test. 4. To show the distribution of patients according to the referral diagnosis, family contact and additional risk factors, 5. To record the patients with confirmed active M. tuberculosis infection. Participants and Methods: A retrospective analysis of Quantiferon-TB Gold plus (QFT-Plus) test results was performed at the Institute of Public Health of the Osijek-Baranja County (IPH OBC), the Department of Microbiology, the Serological Diagnostics Department. The study included samples from patients referred by primary health care practitioners, epidemiologist specialists or departmental doctors of the Clinical Hospital Center (CHC) Osijek. Results: During the five-year period (2012 – 2016), 2 198 blood samples were analyzed at the IPH OBC microbiology department using the QFT-Plus test. The results of the analysis were positive in 549 (25%), negative in 1 566 (73%) and unclear in 50 (2%) samples. The most frequent tests for patients with immunosuppressive therapy totaled 679 (31%) for a five-year period. A total of 54% (293 samples) of positive findings were analyzed from samples sent by primary health care specialists, 51 (10%) of positive samples were from the Department of Pediatrics, 43 (8%) from the Department of Dermatology, 20 (4%) from the Department of Gastroenterology, 31 (6%) from the Department of Rheumatology and 16 (3%) from The Department of Infectious Diseases. Conclusion: The use of in vitro IGF QFT-plus test is important in immunodiagnostics of tuberculosis. It has a significant role in detecting LTBI where, along with the standard methods, it contributes to the prevention of tuberculosis, especially in risk groups.