Oral salbutamol in a dose 0.15 mg/kg of body weight was compared to a total dose of 0.2 mg of salbutamol aerosol in its ability to produce bronchodilation and to prevent exercise-induced bronchospasm (EIB) in 16 asthmatic children in a single-blind crossover study. The degree of bronchodilation seen 120 minutes after the oral salbutamol was equal to that seen 40 minutes after the salbutamol aerosol as assessed by peak expiratory flow (PEF), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), forced expiratory flow during the middle half of the FVC (FEF25-75%), and maximum expiratory-flow after 75% of the FVC had been expired (V25). With respect to changes in PEF and FEV1, both active agents were equally effective in blocking EIB following a standardized treadmill exercise test. However, in assessing changes in FEF25-75%, and V25 following exercise, the aerosol was slightly but significantly more effective than the oral preparation in blocking EIB. Oral salbutamol was clinically effective in preventing EIB for 4.9 to 5.8 hours. The aerosol route has the advantages of a faster onset of action, fewer side effects, and greater protection against EIB with respect ot small airways function. Nevertheless, for patients who are unable to use a metered aerosol, oral salbutamol is a useful alternative both as a bronchodilator and in preventing EIB.