This report updates and supersedes previous recommendations (MMWR 1991;40[No. RR-5]:27-33) for the use of anergy skin testing in conjunction with purified protein derivative (PPD)-tuberculin skin testing of persons infected with human immunodeficiency virus (HIV). In February 1997, CDC convened a meeting of consultants to discuss current information regarding anergy skin testing, PPD skin testing, and tuberculosis (TB) preventive therapy for HIV-infected persons. In formulating these recommendations, CDC considered the results of this meeting, as well as a review of published studies pertaining to PPD and anergy skin testing of persons who are infected with HIV. Isoniazid preventive therapy is effective in reducing the incidence of active TB among persons who have HIV infection and latent TB. Because of the complications associated with TB disease in HIV-infected persons, these persons must be screened for tuberculin infection. HIV-infected persons who have positive reactions to skin testing with PPD tuberculin should be evaluated to exclude active TB and offered preventive therapy with isoniazid if indicated. However, HIV-infected persons may have compromised ability to react to PPD-tuberculin skin testing, because HIV infection is associated with an elevated risk for cutaneous anergy. Anergy testing is a diagnostic procedure used to obtain information regarding the competence of the cellular immune system. When a clinician elects to use anergy testing as part of a multifactorial assessment of a person's risk for TB, the two Food and Drug Administration-approved Mantoux-method tests (mumps and Candida), used together, with cut-off diameters of 5 mm of induration, are recommended. Efforts to apply the results of anergy testing to preventive therapy decisions must be supplemented with information concerning the person's risk for infection with Mycobacterium tuberculosis. Factors limiting the usefulness of anergy skin testing include problems with standardization and reproducibility, the low risk for TB associated with a diagnosis of anergy, and the lack of apparent benefit of preventive therapy for groups of anergic HIV-infected persons. Therefore, the use of anergy testing in conjunction with PPD testing is no longer recommended routinely for screening programs for M. tuberculosis infection conducted among HIV-infected persons in the United States.