Thirty-six acutely III, hospitalized patients with acute exacerbations of obstructive airway disease and a greater than 10% increase in forced expiratory volume in 1 s after administration of aerosolized bronchodilator were randomized to receive either metaproterenol sulfate delivered by updraft-compressor nebulization (UDN) or terbutaline sulfate delivered by metered-dose inhaler (MDI) with a spacer. Serial analyses of pulmonary function measurements were performed with the use of 95% confidence intervals for the percentage response ratios of MDI to UDN. The response to MDI was at least equivalent to that of UDN, and MDI use was associated with no prolongation of hospital stay. Equivalent bronchodilation was achieved with MDI therapy with a lower daily charge for therapy for each patient and less respiratory therapist time. In hospitalized bronchodilator-responsive patients with acute exacerbations of obstructive airway disease, the MDI/spacer combination is the preferred approach when the status of the patient allows its use.