Detection of latent tuberculosis infection is an important step in the control 
of tuberculosis. The tuberculin skin test is the only proven method for 
identifying tuberculosis infection in patients who do not have tuberculosis 
disease. The prevalence of tuberculosis infection among hospitalized patients in 
a pneumological department of an inner-city hospital was evaluated, using the 
intradermal tuberculin skin test (Mantoux technique). Interpretation of the 
Mantoux test was based on the size of induration in millimeters and the 
individual risk profile of the patients, according to the guidelines of the 
American Thoracic Society and the Centers for Disease Control, revised in 1989. 
Of 697 tested patients, 252 showed test results consistent with tuberculosis 
infection (36.2%). 55 of these 697 patients had active tuberculosis disease or a 
prior history of tuberculosis (7.9%). A positive tuberculin skin test was found 
in 197 of 642 patients (30.7%) with a diagnosis different from tuberculosis 
(COPD, pneumonia, cancer and others). In our study, the sensitivity of the 
tuberculin skin test for active tuberculosis infection was 95%. The present 
study revealed a high prevalence of tuberculosis infection among hospitalized 
patients in a pneumological department. Further studies are needed to assess the 
usefulness of routine tuberculin skin testing in hospitalized populations.