Undertreatment of chronic asthma may reflect uncertainty as to how it may be best controlled. We compared the effects of increased inhaled corticosteroid vs regular inhaled bronchodilator in 32 adult asthmatics. During three 16-week treatment periods, comprising baseline inhaled corticosteroid (mean 505 micrograms daily) and on-demand beta-agonist, baseline inhaled corticosteroid and increased (regularly scheduled four times daily) beta-agonist, and increased inhaled corticosteroid (mean 1478 micrograms daily) and on-demand beta-agonist, subjects recorded symptoms, morning and evening peak flow, and additional medication. Of 25 subjects whose control differed significantly between treatments with baseline vs increased corticosteroid, 22 (88 percent) favored the increased dosage (p < 0.001). Of 28 subjects whose control differed between treatments with regular beta-agonist vs increased corticosteroid, 24 (86 percent) were better controlled with increased inhaled corticosteroid and were worse with regular beta-agonist (p < 0.001). Only one quarter the number of exacerbations were experienced during treatment with increased inhaled corticosteroid. Upper airway adverse effects were minor and easily controlled. Hence, asthma with persistent symptoms was better controlled by increased inhaled corticosteroid therapy than by increased use of inhaled beta-agonist.