Asthma prevalence has risen substantially in recent decades and is an increasing cause of disability for American children. Concern about the rise in morbidity has led to treatment guidelines and a growing body of clinical research. Recent trials continue to support the role of inhaled corticosteroids as the most effective therapy to control airway inflammation associated with persistent asthma. Growth suppression due to inhaled corticosteroids has also been well documented, although the long-term effects and relative potencies of different agents require further study. Other anti-inflammatory agents such as cromolyn and the new class of leukotriene receptor antagonists have demonstrated benefit in milder patients. Leukotriene receptor antagonists and long-acting beta2-agonists may allow for reduction of inhaled steroid doses. Control of environmental allergens and irritants is essential. New evidence suggests an increasingly important role for allergen immunotherapy.