Approximately 30 cases of tuberculosis are diagnosed in our hospital each year. Because three of our nurses contracted tuberculosis in 1998, we implemented the following control measures for tuberculosis : (1) immediate examination, diagnosis, and treatment in suspected cases; (2) screening of all health-care workers with a two-step tuberculin skin test (TST); (3) examination of all persons exposed to tuberculosis-infected persons; and (4) greater awareness of tuberculosis. We offered prophylactic medications to all exposed persons with a TST reaction greater than 20 mm. These control measures increased the numbers of outpatients who were examined and treated, and decreased the prevalence of tuberculosis among long-term inpatients. High-risk indices also decreased over a 2-year period. Forty-seven staff members showed TST reactions, and 5 of them received prophylactic medication. No cases of tuberculosis developed in staff members exposed to tuberculosis-infected persons. However, tuberculosis developed in one staff member who had a strong TST reaction at the start of employment. In this case, results of TSTs previously administered to all health-care workers was useful for estimating the prevalence of infection. We used a new method for diagnosing tuberculosis in 27 persons believed to be infected. Of these 27 persons, 5 (19%) showed reactions greater than pseudopositive reactions and were given prophylactic medication. Early diagnosis of infected persons, examination of persons exposed to tuberculosis, and greater disease awareness are important measures for monitoring tuberculosis and controlling its spread.