Fifty percent or less of adult patients can be expected to be able to use the conventional metered dose inhaler (MDI) efficiently if the only tuition they receive is the manufacturer's instruction pamphlet and a high proportion of patients should be expected to develop a poor inhalation technique unless their ability to use an MDI is checked regularly. Because of these problems I believe that the future of the conventional MDI is limited. The new generation of inhalation devices have exciting design features and are undoubtedly better than established inhalation systems in that they are as effective and much easier to use. When these new devices are all available for the delivery of bronchodilators and corticosteroids there is no doubt that many patients will benefit. They should be prescribed in preference to the MDI for all patients whose ability to use a conventional pressurized inhaler is not routinely assessed prior to the institution of therapy and at regular intervals thereafter.