Thirty-five separate episodes of acute bronchial asthma were studied in 21 asthmatic children. The bronchodilator, cardiovascular, and tremorogenic responses following three modes of administration of salbutamol were compared: open continuous nebulization (ON), closed-port intermittent nebulization (CN), and oral route (OR), for a period of 8 hours. Eleven acute attacks were treated by ON, 11 by CN, and 13 by OR. Pulmonary function was evaluated by clinical assessment and by the spirometric indices FEV1 and FEF25-75. Tremor was objectively measured, as well as heart rate (HR), respiratory rate (RR), and blood pressure (BP). Fastest onset of bronchodilator action, maximal response, and longest duration were seen when the drug was administered by the CN. Onset of tremorogenic effect was registered at 5 minutes when salbutamol was used by CN and ON and at 30 minutes when used by OR. During the first 30 minutes, tremor was significantly greater when salbutamol was used by CN than by OR. There were minor cardiovascular effects, except regarding HR after CN, which was significantly greater than after OR, at 5 and 30 minutes. Our findings indicate the inhaled route as the most effective route for administration of salbutamol to treat acute bronchospasm in children. The use of CN is a good alternative to jet nebulizers, but the greater dose of drug effectively administered by this system can briefly cause more tremor and heart acceleration.