The correct use of inhalation devices is an inclusion criterion in many comparative studies. However, patients can make errors, thus compromising the effectiveness of their own inhaler. The aim of the study is to evaluate inhaler use by patients with chronic obstructive pulmonary disease (COPD) [n = 984]. General practitioners assessed inhalation technique, using a specific checklist previously established for each inhaler model (Aerolizer, Autohaler, Diskus, a pressurised metered-dose inhaler (pMDI) or a Turbuhaler). A total of 24% of the patients using a pMDI did not make an error compared with 34-40% of those using breath-actuated devices. The frequency of critical errors varied according to the device: 11.5-14.9% of the subjects using an Aerolizer, Autohaler or Diskus versus 37.4% and 38.1% of the patients using a pMDI and a Turbuhaler, respectively. The proper use of the Turbuhaler is often overestimated (24.7%) compared with the pMDI (2.1%). The development of educational programmes for patients and prescribers is needed to improve the management of COPD.