Many patients with asthma or chronic obstructive pulmonary disease (COPD) use their inhaler ineffectively. Several studies revealed that inhaler-specific design features contributed significantly to the failure rate, which clearly demonstrates the need for developing more "foolproof" inhalers. This study compared ease of use and patient preference of the Diskus/Accuhaler (DA) with the Turbuhaler (TH). Fifty patients with asthma or COPD aged 15 years and older were included in a randomized, crossover comparison of DA with TH regarding patient preference and ease of use. All had to be naïve to DA and TH, but currently had to be using inhaled medication with another device. Inhalation technique was assessed using inhaler-specific checklists and patients had to state a preference for DA or TH regarding various aspects, as well as overall preference. With DA 46 patients (92%) made no errors regarding essential inhalation maneuvers, compared to 37 patients (74%) using TH (p = 0.023). This difference is exclusively caused by not loading the TH properly. When patients were asked which inhaler they would prefer, 17 wanted the DA, 25 the TH, and 8 did not state a preference. The difference was not significant. TH was favored over DA regarding factors related to size and the number of available dosages. The counting mechanism of the DA was preferred over the TH. It seems that patients have a clear, although not statistically significant, preference for TH, but with the DA fewer patients make crucial errors.