OBJECTIVES: Health care workers are a population at risk of Latent Tuberculosis Infection (LTI), which is usually detected by the Tuberculin Skin Test (TST). In vitro immunological tests such as QuantiFERON-TB Gold® (QFT-G) have been recently recommended for LTI screening in health care workers. We compared direct and indirect costs of two LTI screening strategies among health care workers in Spain: TST and QFT-G. METHODS: This was a comparative cost study conducted from a societal perspective, using data on costs and results from a prospective observational study carried out in a Spanish public hospital, where the 2 screening alternatives were concurrently applied to a cohort of 134 health care workers.   RESULTS: In a base-case analysis, the costs of the QFT-G test amounted €42.5 per screened health care worker and those of the TST €39.5. Both tests varied in their cost structure: in the case of TST, most of the total costs (70%) were indirect costs, basically time spent by the participants, whereas QFT-G was more expensive in terms of fungible material, which meant 50% of the total costs. The results are sensitive to the hourly wages of the participants and to the estimation of the time spent by them in the tests.  CONCLUSIONS: This cost study showed that, in the conditions of Spanish health care system, the societal costs of the new QFT-G are comparable to those of the TST; however, their cost structures vary considerably. Therefore, these results could change if applied in other countries with different relation between salaries and prices.