Twenty-five subjects with moderate to severe chronic obstructive airway disease were studied to compare the effect of ipratropium bromide, albuterol, and placebo on the forced expiratory volume in 1 s, (FEV1), forced vital capacity, heart rate, and blood pressure during six hours. Ipratropium produced a significantly greater improvement than albuterol in the FEV1 at 30 minutes and at 3, 4, and 5 hours and in the forced vital capacity at one through six hours. Fifteen subjects did not demonstrate a 15% improvement and at least a 200-mL increase in the FEV1, 15 minutes after metaproterenol sulfate aerosol. All 15 did improve after ipratropium therapy during the study. Ipratropium was effective significantly longer than albuterol. Subjects with better peak responses to ipratropium had a lower FEV1 percent predicted and a greater pack-year smoking history. In patients with chronic obstructive airway disease, ipratropium produces a longer duration of action than albuterol. It is more effective than albuterol in treating severely obstructed individuals and those not responding to metaproterenol. It is equally effective in treating others.