Inhaled corticosteroids modify some but not all features of airway inflammation seen in asthma. ICS remain the most effective class of medications currently available to treat persistent asthma and result in few clinically relevant adverse effects when used in low-moderate doses. ICS activity is enhanced when used in combination with LABA and, to a lesser degree, LTRAs. ICS are well tolerated in adults. Daily doses of ICS may not be required to exceed 200 micrograms of FP equivalents. From an economic standpoint, ICS provide health care savings because of reductions in asthma hospitalization. The impact of early introduction of ICS in the disease course of asthma remains unresolved. The use of ICS in patients whose asthma is mild, with essentially normal lung function, and infrequent symptoms also remains unstudied. For the time being, ICS remain the first line of asthma treatment for adults with persistent disease.