Twenty subjects with clinically stable asthma were treated in double-blind crossover manner with inhaled and oral metaproterenol, alone and in combination. The combination of inhaled and oral metaproterenol resulted in a greater degree of bronchodilation than either inhaled or oral alone. Inhaled metaproterenol was not associated with any significant side effects. Oral metaproterenol was associated with a small but significant increase in pulse rate and systolic blood pressure, and a small incidence of unpleasant sensations such as tremor and palpitation. Older subjects were more likely to experience the unpleasant sensations, whereas younger subjects were more likely to experience the increase in pulse rate.