Tuberculosis (TB) remains an important public health problem worldwide, resulting in a estimated 8 to 10 million new cases and 2 to 3 million deaths each year. Between 1953 and 1985, the number of TB cases in the US declined by an average of 6% per year. However, since 1985, TB has been increasing in the US. Approximately 64,000 additional cases of the disease have been reported beyond the number expected had the rate of decline observed from 1980 to 1984 continued from 1985 through 1993. Increases in the number of TB cases have been significant in racial and ethnic minorities, in persons born outside the US, and in children less than 15 years of age. Infection with the human immunodeficiency virus (HIV) has also been recognized as a major risk factor for the development of active TB in persons with latent Mycobacterium tuberculosis infection. The unusual radiographic findings and the increased likelihood of extrapulmonary TB in HIV-infected persons make diagnosis of the disease problematic. Lastly, concomitant with the resurgence of TB has been the emergence of drug resistance. All of these factors make successful control of TB in the US difficult.