To evaluate the role of inhaled ipratropium bromide in acute asthma, a double-blind study of 384 emergency department patients compared the effect of the combination of ipratropium and albuterol with that of albuterol alone. Patients were randomized to receive nebulizer treatments with either 2.5 mg of albuterol or 2.5 mg of albuterol mixed with 0.5 mg of ipratropium bromide at entry and at 45 min. Spirometry, vital signs, and oxygen saturation were measured before and at 45 and 90 min following the nebulizer treatments. Serum potassium levels were obtained at entry and 90 min. The two groups did not differ significantly in age (mean +/- SD = 33.4 +/- 9.3 and 32.5 +/- 9.7 years for the albuterol and ipratropium group and the albuterol group, respectively), baseline FEV1 (mean +/- SD = 1.22 +/- 0.42 and 1.25 +/- 0.44 L respectively), or prior use of asthma medications. At 45 min, there were significantly more responders (15% increase in FEV1 over baseline) in the group receiving albuterol and ipratropium compared with albuterol and saline solution (85% and 78%, respectively; p = 0.045), but the median change in FEV1 from baseline did not differ (0.530 L for the albuterol and ipratropium group and 0.420 L for the albuterol and saline solution group; p = 0.347). By 90 min, the percentage of responders did not differ (88% and 89%, respectively), and the median change in FEV1 was 0.680 L for the group receiving albuterol and ipratropium and 0.650 L for the group receiving albuterol and saline solution (p = 0.693). There were no significant adverse events experienced by patients in either group. Furthermore, there were no significant differences in the number of patients requiring additional therapy in the emergency department or hospitalization. We conclude that in this population of inner city asthmatics, we were unable to demonstrate significant additive benefit of nebulized ipratropium bromide to nebulized albuterol.