OBJECTIVE To compare bronchodilation, chronotropic effects, and side effects of the same dose of nebulized albuterol when given by either intermittent or continuous administration. METHODS A randomized assignment of patients to one of the two methods of albuterol nebulization. METHODS Adult emergency department in an urban public hospital. METHODS Adult patients with acute exacerbations of asthma. METHODS Administration of 30 mg albuterol given over 110 minutes by either continuous or intermittent aerosolization. METHODS FEV1, forced vital capacity, heart rate, and systolic and diastolic blood pressures were measured immediately before treatment and then hourly for two hours. Side effects, symptoms, subsequent admission, and discharge also were noted. RESULTS An overall significant decrease in heart rate was observed, indicating the lack of significant chronotropic effects with this dose of albuterol. Both treatments resulted in significant spirometric improvement without a significant treatment difference for the entire group. A difference, however, was found in the relative rates of FEV1 improvement with the two treatments depending on whether patients had an initial FEV1 less than or more than 50% predicted (P = .05). A secondary analysis on patients with an initial FEV1 less than percent predicted demonstrated a higher rate of percent predicted FEV1 increase with the continuously nebulized albuterol group (P = .03). CONCLUSIONS This study demonstrates that albuterol can be given safely at this dose by either intermittent or continuous nebulization. Future studies should examine whether continuous nebulization has a reproducible advantage over intermittent nebulization in patients with more severe obstruction.