The acute cardiopulmonary effects of oral albuterol, 4 mg, metaproterenol sulfate, 20 mg, and terbutaline sulfate, 5 mg, were compared over eight hours in 20 moderate to severe asthmatics. The magnitude and time course of bronchodilation following albuterol and terbutaline were comparable. Albuterol and terbutaline had a duration of action of at least eight hours and produced significantly greater bronchodilation than metaproterenol from six to eight hours. Metaproterenol produced a greater degree of bronchodilation than albuterol and terbutaline 30 minutes after drug dosing. Significantly fewer patients receiving albuterol experienced one or more central nervous system or musculoskeletal side effects than patients receiving terbutaline. These findings imply possible therapeutic advantages of oral albuterol and terbutaline wifh respect to dosing frequency, while the more rapid onset of oral metaproterenol suggests that it may have an advantage when used on an as-needed basis.