In many urban settings, a significant proportion of hospital services are directed toward HIV-related illnesses. Asthma, however, has long been associated with a high rate of hospitalization for patients with exacerbations of disease. It is therefore not surprising or unusual to encounter patients who have both HIV infection and asthma. To the allergist, HIV-infected patients have unique problems relating to hypersensitivity. To the HIV specialist, the differential diagnosis for obstructive pulmonary disease is crucial to establish for patients with bronchospasm of new onset. For any physician who treats patients with both disorders, an understanding of drug interactions is essential for proper management of patients, whose therapy is constantly being revised and updated. This article reviews special considerations in the diagnosis and treatment of patients with asthma and HIV infection.