An association between tuberculosis and HIV infection is becoming increasingly evident. HIV seropositivity has been seen in nearly 30% of some populations with tuberculosis. In other populations nearly 25% of patients with AIDS had tuberculosis. Clinically these patients present with nonspecific findings including weight loss, night sweats, and fever. The symptoms are generally gradual in onset and last for several weeks. Early in the course of HIV infection a PPD skin test may be positive and the radiographic findings may be similar to those seen in individuals with normal immunity. Thus, upper lobe heterogeneous and cavitary opacities may be seen on the chest radiograph. In late HIV infection, however, the PPD skin test is generally negative and the radiograph demonstrates lymphadenopathy and diffuse heterogeneous parenchymal opacities. Tuberculosis should be suspected in HIV-infected patients when diffuse interstitial lung disease is demonstrated in conjunction with hilar or mediastinal lymph node enlargement. In contrast, lymphadenopathy is not expected in the most common opportunistic lung disease, Pneumocystis carinii pneumonia. Standard antituberculous drug therapy is extremely effective in treating tuberculosis in this setting.