The aim of this study was to investigate the effects of nebulized ipratropium in patients with acute asthma in order to determine whether it augments the bronchodilator effect of a beta agonist drug. A total of 28 patients with acute asthma were randomly allocated to treatment every six hours with either 1 mg nebulized fenoterol (group A) or 1 mg fenoterol and 0.5 mg ipratropium (group B). There was no significant difference between the mean FEV1 of the two groups prior to treatment and increasing the dose of fenoterol from 1 mg to 2 mg did not increase the response. However the mean change in FEV1 after 48 hours (expressed as a percentage of the predicted maximal response) was 40.1 +/- 7.2 percent in group A and 54.3 +/- 9.2 percent in group B (p less than 0.005). It was concluded that the response of patients with acute asthma to fenoterol was significantly enhanced by the addition of the anticholinergic agent ipratropium bromide.