OBJECTIVE To determine the efficacy of combination therapy using atropine sulfate and albuterol in the treatment for an acute exacerbation of asthma. METHODS A prospective, randomized double-blind, placebo-controlled study was performed in the ED of a large, inner-city, university-affiliated teaching hospital. Participants were a convenience sample of patients presenting to the ED between September 1993 and March 1994 with acute exacerbations of their asthma. Patients judged to be in extremis were excluded. All patients received 3 nebulized treatments with 2.5 mg of albuterol at 0, 30, and 60 minutes. Patients were randomized into 1 of 3 groups with the following added to their nebulizer solutions: 1) saline placebo during all 3 treatments; 2) 2.0 mg atropine sulfate added to the first nebulizer and saline in the second and third; or 3) 2.0 mg atropine to the first and third treatments (with saline in the second). No other medication was administered during the study period. At 90 minutes, the patients were evaluated for admission or release from the ED according to predetermined criteria, and additional medications were given as necessary. Vital signs, peak expiratory flow rate (PEFR), degree of wheezing, level of distress, and side effects were measured before and after each nebulizer treatment. RESULTS Of the 153 patients eligible for the study, 126 completed the entire study protocol. There was no significant difference between the 3 groups on any parameter studied, including improvement of PEFR, vital signs, or level of distress. There was no difference in the admission rate between the 3 groups, nor was there a difference in the incidence of side effects among the groups. CONCLUSIONS In this study population, combination therapy with atropine sulfate and albuterol offered no significant benefit over the use of albuterol alone in the treatment for acute exacerbation of asthma.