The purpose of this study was to determine the efficacy and toxicity of a standard antituberculosis regimen in patients with human immunodeficiency virus (HIV) infection. We prospectively evaluated 89 patients with tuberculosis and HIV infection at an urban medical center. Eighty-two patients received isoniazid, rifampin, and pyrazinamide, with or without ethambutol, for 2 mo, followed by isoniazid and rifampin for 7 mo. Seven patients received other regimens because of drug resistance or intolerance. Therapy was self-administered in 57 patients and directly observed in 32 cases. All patients showed rapid clinical improvement during the first month of therapy, and sputum cultures reverted to negative after 3 mo in 52 of 54 patients from whom specimens were obtained. Adverse reactions to isoniazid or rifampin prompted alterations in antituberculosis regimens in five patients (6%). Forty patients (45%) died during follow-up, and tuberculosis was a potential contributory cause of death in three cases. Treatment failure occurred in five patients (6%), four of whom were noncompliant with therapy. The fifty patient had an isoniazid-resistant organism. No relapses occurred in 916 patient-months of follow-up posttreatment. We thus conclude that the 9-mo regimen used for treatment of drug-susceptible tuberculosis in HIV-infected patients is effective and well tolerated.