A review with 22 references concerning patient care issues in relation to using hydrofluorocarbon substitutes for chlorofluorocarbon propellants in metered dose inhalers (MDI) is given.Topics discussed include: respiratory disease; respiratory therapy (inhalation delivery system [MDI, nebulizers, dry powder inhalers], preservation of therapy options); selecting hydrofluorocarbons as replacements for chlorofluorocarbons in MDI (criteria for an MDI propellant, the choice of hydrofluorocarbons, transition to hydrofluorocarbon MDI); potential future technologies; and hydrofluorocarbon emissions from MDI (preliminary emissions projections, steps to minimize emissions).