There is a growing appreciation of asthma as an inflammatory disease. Immunotherapy may play a role in modulating immunologic responses including inflammatory mediator production from cells involved in asthma. Studies of pollen-sensitive asthma have demonstrated beneficial effects of specific immunotherapy for grass, birch, and ragweed pollen-induced asthma. However, risk of systemic reactions exists, especially when specific immunotherapy is administered during the specific allergen season. House dust mite immunotherapy has benefitted asthmatic children more than adults. Patients having unstable pulmonary function may be at the highest risk of having systemic reactions to such immunotherapy. Animal dander immunotherapy and immunotherapy for molds including Clasdosporium and Alternaria may improve selected asthmatic patients. Avoidance of the offending allergen is still, however, the preferred mode of treatment of allergic asthma.