Respimat (RMT) is a reusable, propellant-free, soft mist inhaler (SMI), a novel device for inhalation therapy. We conducted a three-period cross-over study to evaluate the safety and efficacy of cumulative doses of ipratropium bromide inhaled from RMT (Two dose levels) or from a pressurized metered dose inhaler (MDI), in 36 patients with chronic obstructive pulmonary disease (COPD). The bronchodilator effect of ipratropium bromide was greater when administered via RMT (10 or 20 microg per puff, given double-blind within device, to total doses of 160 or 320 microg) than via MDI (20 microg per puff, total dose 320 microg). The bronchodilator effects of the 160 and 320 microg doses delivered via RMT were similar. Cumulative ipratropium bromide doses of 320 microg given via MDI or RMT and 160 microg given via RMT produced similar safety profiles. Between 45 min after the first drug inhalation and 45 min after the final dose, greater bronchodilatory effect was obtained from half the cumulative dose of ipratropium (RMT 10 microg per puff) when compared with the MDI (20 microg per puff). Therefore, ipratropium bromide delivered by RMT is as safe as, and can be more effective than, the MDI on acute administration in patients with COPD.