Objective: This study compared the bronchodilator effects of Short-acting (salbutamol and procaterol) and long-acting (salmeterol and formoterol) beta(2)-agonists in children with bronchial asthma. Patients: Twenty-seven (Is male, 9 female) children with bronchial asthma were enrolled in the study. Drugs were administered randomly in the morning for 5 days as follows: 1 single dose of two short-acting beta(2)-agonists, salbutamol 200 mu g and procaterol 20 mu g, and two long-acting beta(2)-agonists salmeterol 50 mu g and formoterol 24 mu g, and placebo. Results: All beta(2)-agonists demonstrated a significantly higher bronchodilator effect than that observed with placebo. This effect appeared to be due to the forced expiratory flows. Formoterol produced a higher bronchodilator effect than salbutamol, and salmeterol showed a bronchodilator effect comparable with salbutamol at 30 minutes but higher than salbutamol after 3 hours. Conclusion: Our study confirmed the efficacy of the bronchodilator effects of the beta(2)-agonists. Salmeterol and formoterol, in particular, produced an improvement in respiratory function with a significant increase in forced expiratory flows in children with bronchial asthma.