In an effort to maximize the efficacy of corticosteroid treatment in asthma and minimize the adverse reactions, steroid therapy has evolved to the inhalation route of administration with aerosol compounds having potent topical antiinflammatory activity and minimal systemic effects. Corticosteroids exhibiting these properties that are available in the U.S. include beclomethasone dipropionate, triamcinolone acetonide, and flunisolide. The success or failure of patient response to orally inhaled corticosteroids is often a function of adequate drug delivery rather than the efficacy of the drug itself. Patients who cannot use the inhaler accurately may benefit from the use of a spacer or reservoir device. The three aerosolized corticosteroids have specific pharmacologic differences; however, none of these differences has translated into a clinically significant advantage or disadvantage of one product over the others. These agents should be considered for adjunctive therapy in patients whose asthma is not adequately controlled by beta-agonist bronchodilators, theophylline, or cromolyn sodium.