The medications prescribed to treat asthma are provided in a range of delivery systems, designed to give patients a choice in how they take their inhaled medication. These include the mainstay of asthma therapy, the metered dose inhaler (MDI), and the breath-operated inhalers. One of the major challenges that all the leading companies in the respiratory area have faced in recent years is the environmental effects of chlorofluorocarbons. The pharmaceutical industry recognized the need to reformulate MDI products containing chlorofluorocarbons, and a number of companies began to develop alternatives in the late 1980s. To help facilitate this change in products, an industry consortium was formed (International Pharmaceutical Aerosol Consortium), and this has managed many of the overarching issues. After an extensive search was conducted, the most suitable alternatives were the hydrofluoroalkanes, which do not contain chlorine, are ozone friendly, and have lower global-warming potentials than the chlorofluorocarbons that they are replacing. To date it is estimated that the industry has invested over $1.0 billion ($US) on global research and development efforts. The first countries to launch the nonchlorofluorocarbon MDIs have been in Europe, and now salbutamol and 2 inhaled steroids are widely available across Europe in their nonchlorofluorocarbon form. Clinical testing has been extensive, and patient acceptance of the new products has proved to be high. Maintaining the smooth progress of the global transition is important, and continued dialogue between all key stakeholders should ensure success in this area. (J Allergy Clin Immunol 1999;104:S268-70.)