Inhaled medications are the mainstay of asthma treatment. This route of administration provides the largest clinical effect with few systemic side-effects. The two main types of delivery systems are pressurized metered-dose inhalers (pMDIs) and dry powder inhalers (DPIs). An ideal inhalation device should be easy to use, provide optimal lung deposition, give minimal oropharyngeal/gastrointestinal deposition, and contain no harmful additives. The advantages of pMDIs are portability, minimal cost, and the low inspiratory flows needed to achieve adequate drug deposition in the lungs. The disadvantages include high oropharyngeal/gastrointestinal deposition, improper use, and the propellants, which can cause bronchoconstriction. The advantages of DPIs are portability and ease of use, because no co-ordination between actuation and inhalation is required, and most are multiple-dose devices. Of the DPIs currently available for clinical use, Turbuhaler® provides the highest lung deposition; twice that of pMDIs. This results both in greater bronchodilation for a given dose of inhaled β2-agonist and, when compared with pMDIs, approximately half of the nominal dose of inhaled corticosteroids from the inhaler device to maintain optimal asthma control. The use of Turbuhaler® may also reduce the topical side-effects associated with high oropharyngeal deposition of corticosteroids.