Current guidelines from the American Thoracic Society and the Centers for Disease Control recommend 6 to 12 months of INH for PPD (purified protein derivative)-positive individuals. Although the effectiveness of this treatment is not known for HIV-infected individuals, several studies using INH to prevent tuberculosis in presumably normal hosts have shown 60 to 80 percent effectiveness. Problems with this treatment include compliance, adverse reaction, and the possibility of not preventing disease due to tuberculosis organisms being resistant to INH. A two-month preventive treatment plan should help in increasing compliance. In addition, the use of two drugs (rifampin / pyrazinamide) may help overcome problems with drug resistance. If this study shows equal or greater effectiveness of the two-month rifampin / pyrazinamide treatment, it could alter the approach to tuberculosis prevention for both HIV-positive and HIV-negative individuals.