Twenty asthmatic children who had daily wheezing requiring constant medi cation as outpatients were given oral metaproterenol or oral theophylline in a randomized double-blind crossover study. Each medication was given for four weeks, after the theophylline dosage necessary to give a therapeutic level was established. Pulmonary function parameters, daily peak-flow measurements and diary symptom scores were statistically comparable in most patients during these four-week intervals. Metaproterenol may be used in place of oral theophylline for at least a four-week interval with no decrease in effectiveness.