BACKGROUND Despite multiple doses of beta2-agonists in the treatment of acute asthma exacerbation, significant residual airways obstruction often remains. OBJECTIVE To determine whether the addition of inhaled ipratropium bromide to salbutamol provides improvement in lung function and clinical asthma symptoms in young children with acute asthma exacerbation. METHODS This study was a prospective, double-blind randomized control trial of children aged 3 to 15 years who presented with an acute asthma exacerbation at the emergency department or outpatient clinic of Thammasat University Hospital, Pathumthani, Thailand, between September 2001 and February 2003. Subjects were randomized to receive 3 doses of nebulized salbutamol mixed with isotonic sodium chloride solution (control) or ipratropium bromide (treatment) every 20 minutes. Additional doses of salbutamol were given every 30 minutes as needed. Asthma outcome measures were evaluated 40, 70, 100, and 120 minutes after baseline. Primary outcomes were the differences in percent change in asthma clinical score and percent change in peak expiratory flow rate (PEFR) from baseline. Secondary outcomes included change in percent predicted PEFR. RESULTS Of 74 children randomized and enrolled in the trial, 71 had complete data for analysis. Thirty-three children were in the control group and 38 were in the treatment group. Both the percent change in PEFR and the change in percent predicted PEFR at any time were higher in the treatment group, but these findings were not statistically significantly different. The number of subjects with at least a 100% percent predicted PEFR at any time point was greater in the treatment group. CONCLUSIONS Although this study did not demonstrate a significant advantage in clinical score and PEFR, the trend toward additional effect of ipratropium bromide was consistent with previous studies.