We studied the safety and efficacy of albuterol (salbutamol) delivered by continuous nebulization (CN) in the initial emergency department treatment of asthma. In a randomized fashion 21 patients received 5 mg of albuterol by bolus nebulization (BN) at time 0 and again 60 minutes later. Twenty-one others received albuterol (0.2 mg/ml) by CN using a calibrated nebulizer with a known output of 25 ml/h. Thus, each patient had received 10 mg of albuterol over two hours. FEV1, blood pressure (BP), heart rate (HR), respiratory rate (RR), and hand tremor were recorded at 30-minute intervals. The FEV1 was 1.48 +/- 0.64 L prior to BN and increased to a maximum of 2.20 +/- 0.94 L (p less than 0.05) 90 minutes later. The FEV1 prior to CN was 1.13 +/- 0.51 L and improved to 2.20 +/- 1.02 L (p less than 0.05) at 120 minutes. The FEV1 did not differ significantly between regimens over the 2-hour period. Both modes of therapy were well tolerated. There was a slight but significant increase in HR at 30 and 90 minutes in the BN group when compared with CN. There was no significant difference in BP, RR, or tremor between the groups. Thus, albuterol by CN was found to be equally effective as the same medication by BN in the early treatment of asthma in patients seen in the emergency department.