OBJECTIVES: This study aimed at assessing patient preferences for different characteristics of Dry Powder Inhalers (DPIs) from patients with asthma and chronic obstructive pulmonary (COPD) disease in France, UK, Spain, Germany and Netherlands using the discrete choice experiment (DCE) method. METHODS: Attributes characterizing DPIs and attribute levels were defined using focus groups among asthma and COPD patients and interviews of health care professionals in France. Those attributes were ease of use, accurate and easy-to-read dose counter, dose confirmation, hygiene of the mouthpiece, flexibility of device handling and use with breathing difficulties. A fractional factorial design including 3 sets of 12 choices was created. Analyses were performed using a ranked ordered logit model. Interactions between attributes and asthma/COPD were tested. RESULTS: Participants included 601 patients with asthma and 491 with COPD. Asthma and COPD patients were on average 43 and 53 years old respectively. Preferences of patients with asthma and COPD were largely similar, but the marginal utility of the cost attribute was higher in asthma patients, compared to COPD, in three countries. In all countries, marginal utilities were highest for ease of use and ability to use the inhaler with breathing difficulties. Estimates of willingness to pay (WTP) for an inhaler requiring one step to prepare a dose instead of four ranged from €3.27 (95% CI: [2.23;4.32]) in asthma patients in Germany to €15.14 [-82.43;112.72]  in asthma/Spain. The estimated WTP for ability to use with breathing difficulties ranged from €2.19 [1.10;3.28] in asthma patients in the Netherlands and €13.68 [-117.77;145.12] in COPD/Spain. The marginal utility of the hygiene of the mouthpiece was not significantly different from zero.  CONCLUSIONS: Despite differences in valuations of attributes between counties, two attributes were consistently found to be the most important: ease of use and ability to use the inhaler in case of difficulties breathing in.