Twelve adult asthmatics inhaled single doses of 0.5, 2.0 or 4.0 mg of terbutaline, respectively, via Turbuhaler, on three separate days. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and pulse rate were measured 15, 30, 45 and 60 min after inhalation from the inhaler and then hourly up to 8 h. The results showed that a more rapid onset of action, a greater maximal response and a longer duration of action can be achieved by exceeding the standard dose of terbutaline of 0.5 mg. The incidence of adverse effects was very low even at the highest dose, 4 mg. This study emphasizes the need for individual dosing of inhaled bronchodilators.