We performed a multicentre, randomised, double-blind (within-device), placebo- and active-controlled, parallel-group study to compare the efficacy and safety of ipratropium bromide plus fenoterol hydrobromide (IB/FEN; Berodual) delivered via the novel, propellant-free Respimat Soft Mist Inhaler (SMI) and from a chlorofluorocarbon (CFC)-metered-dose inhaler (MDI) in moderate-to-severe chronic obstructive pulmonary disease (COPD) patients. After 2-weeks' run-in (CFC-MDI [IB 20 microg/FEN 50 microg per actuation] two actuations q.i.d. [MDI 40/100]), 892 patients were randomised to Respimat SMI containing IB 10 microg/FEN 25 microg (Respimat SMI 10/25), IB 20 microg/FEN 50 microg (Respimat SMI 20/50) or placebo (one actuation q.i.d.), or a CFC-MDI containing IB 20 microg/FEN 50 microg (MDI 40/100) or placebo (two actuations q.i.d.) for 12 weeks. Analysis of the primary endpoint (change in forced expiratory volume in 1 s [FEV1] in the first 60 min after dosing [area under the curve; AUC0-1h]) on day 85 showed that the efficacy of Respimat SMI 20/50 (but not Respimat SMI 10/25) was not inferior to that of MDI 40/100. The safety profile of Respimat SMI was comparable to CFC-MDI. Switching from MDI 40/100 to Respimat SMI was well tolerated. Respimat SMI enables a 50% reduction of the nominal inhaled dose of IB/FEN in COPD patients while offering similar therapeutic efficacy and safety to the CFC-MDI.