This report updates and replaces previous recommendations regarding the use of Bacillus of Calmette and Guerin (BCG) vaccine for controlling tuberculosis (TB) in the United States (MMWR 1988;37:663-4, 669-75). Since the previous recommendations were published, the number of TB cases have increased among adults and children, and outbreaks of multidrug-resistant TB have occurred in institutions. In addition, new information about the protective efficacy of BCG has become available. For example, two meta-analyses of the published results of BCG vaccine clinical trials and case-control studies confirmed that the protective efficacy of BCG for preventing serious forms of TB in children is high (i.e., > 80%). These analyses, however, did not clarify the protective efficacy of BCG for preventing pulmonary TB in adolescents and adults; this protective efficacy is variable and equivocal. The concern of the public health community about the resurgence and changing nature of TB in the United States prompted a re-evaluation of the role of BCG vaccination in the prevention and control of TB. This updated report is being issued by CDC, the Advisory Committee for the Elimination of Tuberculosis, and the Advisory Committee on Immunization Practices, in consultation with the Hospital Infection Control Practices Advisory Committee, to summarize current considerations and recommendations regarding the use of BCG vaccine in the United States. In the United States, the prevalence of M. tuberculosis infection and active TB disease varies for different segments of the population; however, the risk for M. tuberculosis infection in the overall population is low. The primary strategy for preventing and controlling TB in the United States is to minimize the risk for transmission by the early identification and treatment of patients who have active infectious TB. The second most important strategy is the identification of persons who have latent M. tuberculosis infection and, if indicated, the use of preventive therapy with isoniazid to prevent the latent infection from progressing to active TB disease. Rifampin is used for preventive therapy for persons who are infected with isoniazid-resistant strains of M. tuberculosis. The use of BCG vaccine has been limited because a) its effectiveness in preventing infectious forms of TB is uncertain and b) the reactivity to tuberculin that occurs after vaccination interferes with the management of persons who are possibly infected with M. tuberculosis. In the United States, the use of BCG vaccination as a TB prevention strategy is reserved for selected persons who meet specific criteria. BCG vaccination should be considered for infants and children who reside in settings in which the likelihood of M. tuberculosis transmission and subsequent infection is high, provided no other measures can be implemented (e.g., removing the child from the source of infection). In addition, BCG vaccination may be considered for health-care workers (HCWs) who are employed in settings in which the likelihood of transmission and subsequent infection with M. tuberculosis strains resistant to isoniazid and rifampin is high, provided comprehensive TB infection-control precautions have been implemented in the workplace and have not been successful. BCG vaccination is not recommended for children and adults who are infected with human immunodeficiency virus because of the potential adverse reactions associated with the use of the vaccine in these persons. In the United States, the use of BCG vaccination is rarely indicated. BCG vaccination is not recommended for inclusion in immunization or TB control programs, and it is not recommended for most HCWs. Physicians considering the use of BCG vaccine for their patients are encouraged to consult the TB control programs in their area.